Yeah I'm sure Showthread is the template you need to put it on all threads,
I was right thought after a quick search we have it on our template postbit for the whole forum.
For those who want to use it on every post, here is a copy of our postbit template the add this button is near the top:
$template_hook[postbit_start]
<table class="tborder" id="post$post[postid]" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
<td class="thead" $post[scrolltothis]>
<div class="normal" style="float:$stylevar[right];border:0px solid black;">
<div style="position:relative;float:left;top:4px;">
<if condition="$show['postcount']">#<a href="showpost.php?$session[sessionurl]p=$post[postid]&postcount=$post[postcount]" target="new" rel="nofollow" id="postcount$post[postid]" name="$post[postcount]"><strong>$post[postcount]</strong></a> </if>
</div>
<div id="bookmarkwidget" style="position:relative;float:left;top:7px;margin-left:8px;">
<!-- AddThis Bookmark Button BEGIN -->
<a href="http://www.addthis.com/bookmark.php" onclick="addthis_url = location.href; addthis_title = document.title; return addthis_click(this);" target="_blank"><img src="http://s9.addthis.com/button1-bm.gif" width="125" height="16" border="0" alt="AddThis Social Bookmark Button" /></a> <script type="text/javascript">var addthis_pub = 'legionofangels';</script><script type="text/javascript" src="http://s9.addthis.com/js/widget.php?v=10"></script>
<!-- AddThis Bookmark Button END --></div>
<div style="position:relative;float:left;margin-left:16px;margin-right:12px;">
<a href="showthread.php?p=$post[postid]"><img src="../ending.png" border="0" alt="Permalink"></a>
</div>
<if condition="$show['reputationlink']">
<span id="reputationmenu_$post[postid]"><a href="reputation.php?$session[sessionurl]p=$post[postid]" rel="nofollow" id="reputation_$post[postid]"><img class="inlineimg" src="$stylevar[imgdir_button]/reputation.png" alt="<phrase 1="$post[username]">$vbphrase[add_to_xs_reputation]</phrase>" border="0" /></a></span>
<if condition="$show['popups']"><script type="text/javascript"> vbrep_register("$post[postid]")</script></if>
</if>
<if condition="$show['infractionlink']"><a href="infraction.php?$session[sessionurl]do=report&p=$post[postid]" rel="nofollow"><img class="inlineimg" src="$stylevar[imgdir_button]/infraction.png" alt="<phrase 1="$post[username]">$vbphrase[add_infraction_for_x]</phrase>" border="0" /></a> </if>
<if condition="$show['reportlink']"><a href="report.php?$session[sessionurl]p=$post[postid]" rel="nofollow"><img class="inlineimg" src="$stylevar[imgdir_button]/report.png" alt="$vbphrase[report_bad_post]" border="0" /></a> </if>
$post[iplogged]
<if condition="$show['inlinemod']">
<input type="checkbox" name="plist[$postid]" id="plist_$postid" style="vertical-align:middle; padding:0px; margin:0px 0px 0px 5px" value="$post[checkbox_value]" />
</if>
</div>
<div class="normal">
<!-- status icon and date -->
<a name="post$post[postid]"><span style="position:relative;top:4px;"><img class="inlineimg" src="$stylevar[imgdir_statusicon]/post_$post[statusicon].gif" alt="$post[statustitle]" border="0" /></span></a>
<if condition="!$show['announcement']">
<span style="position:relative;top:6px;">$post[postdate]<if condition="!$show['detailedtime']">, $post[posttime]</if></span>
<else />
<phrase 1="$post[startdate]" 2="$post[enddate]">$vbphrase[x_until_y]</phrase>
</if>
$post[firstnewinsert]
<!-- / status icon and date -->
</div>
</td>
</tr>
<tr>
<td class="alt2" style="padding:0px">
<!-- user info -->
<style>
table {border:0px solid red;}
td {border:0px solid blue;}
</style>
<table cellpadding="0" cellspacing="0" border="0" width="100%">
<tr>
<if condition="$show['avatar']"><td class="none"><a href="member.php?$session[sessionurl]u=$post[userid]"><img src="$post[avatarurl]" $post[avwidth] $post[avheight] alt="<phrase 1="$post[username]">$vbphrase[xs_avatar]</phrase>" border="0"
style="padding:0 5px 0 5px;" /></a></td></if>
<td nowrap="nowrap">
<!-- name/joindate/posts -->
<div id="postmenu_$post[postid]">
<if condition="$show['profile']">
<a class="bigusername" href="member.php?$session[sessionurl]u=$post[userid]"><span style="font-family:palatino linotype;">$post[musername]</span></a>
$post[onlinestatus]
<script type="text/javascript"> vbmenu_register("postmenu_$post[postid]", true); </script>
<else />
$post[musername]
</if>
</div>
<div class="smallfont">
<if condition="$post['joindate']"><div>$vbphrase[join_date]: $post[joindate]</div></if>
<if condition="$post['field2']"><div>$vbphrase[location_perm]: $post[field2]</div></if>
<if condition="$post['age']"><div>$vbphrase[age]: $post[age]</div></if>
<div>
$vbphrase[posts]: $post[posts]
</div>
$template_hook[postbit_userinfo_right_after_posts]
<if condition="$show['infraction']"><div>$vbphrase[infractions]: $post[warnings]/$post[infractions] ($post[ipoints])</div></if>
<if condition="$show['reputation']"><if condition="$show['reppower']">$vbphrase[reppower]: <span id="reppower_$post[postid]_$post[userid]">$post[reppower]</span> </if><div><span id="repdisplay_$post[postid]_$post[userid]">$post[reputationdisplay]</span></div></if>
$template_hook[postbit_userinfo_right]
<div>$post[icqicon] $post[aimicon] $post[msnicon] $post[yahooicon] $post[skypeicon]</div>
</div>
<!-- end joindate/posts -->
</td>
<td width="100%"> </td>
<td nowrap="nowrap" width="518px" align="right" valign="middle">
<!-- rank/title -->
<div id="box" style="position:relative;height:125px;width:518px;border: 0px solid red;">
<div id="wingbg" style="position:absolute;float:right;background-image:url(http://legionofangels.net/finalwing.png);height:115px;width:518px;
bottom:0; right:0;">
<div id="verticalpos" style="height:50px;position:relative;top:50%; margin-top:-25px;text-align:center;">
<div id="rightalign" style="width:260px;position:relative;padding-left:250px;margin-left:auto; margin-right:auto; border:0px solid red;">
<!-- <if condition="$post['usertitle']">
<div>$post[usertitle]</div></if> -->
<if condition="$post['rank']">
<div>$post[rank]</div>
</if>$template_hook[postbit_userinfo_left]
</div>
</div>
</div>
<!-- rank/title end -->
</td>
</tr>
</table>
<!-- / user info -->
</td>
</tr>
<tr>
<td class="alt1" id="td_post_$post[postid]">
<!-- message, attachments, sig -->
$template_hook[postbit_messagearea_start]
<if condition="$show['messageicon'] OR $post['title']">
<!-- icon and title -->
<div class="smallfont">
<if condition="$show['messageicon']"><img class="inlineimg" src="$post[iconpath]" alt="$post[icontitle]" border="0" /></if>
<if condition="$post['title']"><strong>$post[title]</strong></if>
</div>
<hr size="1" style="color:$stylevar[tborder_bgcolor]" />
<!-- / icon and title -->
</if>
<!-- message -->
<div id="post_message_$post[postid]">$post[message]</div>
<!-- / message -->
<if condition="$show['attachments']">
<!-- attachments -->
<div style="padding:$stylevar[cellpadding]px">
<if condition="$show['thumbnailattachment']">
<fieldset class="fieldset">
<legend>$vbphrase[attached_thumbnails]</legend>
<div style="padding:$stylevar[formspacer]px">
$post[thumbnailattachments]
</div>
</fieldset>
</if>
<if condition="$show['imageattachment']">
<fieldset class="fieldset">
<legend>$vbphrase[attached_images]</legend>
<div style="padding:$stylevar[formspacer]px">
$post[imageattachments]
</div>
</fieldset>
</if>
<if condition="$show['imageattachmentlink']">
<fieldset class="fieldset">
<legend>$vbphrase[attached_images]</legend>
<table cellpadding="0" cellspacing="$stylevar[formspacer]" border="0">
$post[imageattachmentlinks]
</table>
</fieldset>
</if>
<if condition="$show['otherattachment']">
<fieldset class="fieldset">
<legend>$vbphrase[attached_files]</legend>
<table cellpadding="0" cellspacing="$stylevar[formspacer]" border="0">
$post[otherattachments]
</table>
</fieldset>
</if>
<if condition="$show['moderatedattachment']">
<fieldset class="fieldset">
<legend>$vbphrase[attachments_pending_approval]</legend>
<table cellpadding="0" cellspacing="$stylevar[formspacer]" border="0">
$post[moderatedattachments]
</table>
</fieldset>
</if>
</div>
<!-- / attachments -->
</if>
$template_hook[postbit_signature_start]
<if condition="$post['signature']">
<!-- sig -->
<div>
__________________<br />
$post[signature]
</div>
<!-- / sig -->
</if>
$template_hook[postbit_signature_end]
<if condition="$show['postedited']">
<!-- edit note -->
<div class="smallfont"> <hr size="1" style="color:$stylevar[tborder_bgcolor]" />
<em>
<phrase 1="$post[edit_username]" 2="$post[edit_date]" 3="$post[edit_time]">$vbphrase[last_edited_by_x_on_y_at_z]</phrase>.
<if condition="$post['edit_reason']">$vbphrase[reason]: $post[edit_reason]</if>
</em>
</div>
<!-- / edit note -->
</if>
<div style="position:relative;float:left;top:10px;border:0px solid red;">
<if condition="$show['redcard']">
<a href="infraction.php?$session[sessionurl]do=view&p=$post[postid]"><img src="$stylevar[imgdir_button]/redcard.png" alt="$vbphrase[received_infraction]" border="0" /></a>
<else />
<if condition="$show['yellowcard']">
<a href="infraction.php?$session[sessionurl]do=view&p=$post[postid]"><img src="$stylevar[imgdir_button]/yellowcard.png" alt="$vbphrase[received_warning]" border="0" /></a>
</if>
</if>
</div>
<div style="margin-top: 10px" align="$stylevar[right]">
<!-- controls -->
<if condition="$post['editlink']">
<img style="display: none" id="progress_$postid" src="$stylevar[imgdir_misc]/progress.gif" alt="$vbphrase[loading_editor_please_wait]" />
<a href="$post[editlink]" name="vB::QuickEdit::$post[postid]"><img src="$stylevar[imgdir_button]/edit.gif" alt="$vbphrase[edit_delete_message]" border="0" /></a>
</if>
<if condition="$post['forwardlink']">
<a href="$post[forwardlink]"><img src="$stylevar[imgdir_button]/forward.gif" alt="$vbphrase[forward_message]" border="0" /></a>
</if>
<if condition="$post['replylink']">
<a href="$post[replylink]" rel="nofollow"><img src="$stylevar[imgdir_button]/<if condition="$post['forwardlink']">reply_small<else />quote</if>.gif" alt="$vbphrase[reply_with_quote]" border="0" /></a>
</if>
<if condition="$show['multiquote_post']">
<a href="$post[replylink]" rel="nofollow" onclick="return false"><img src="$stylevar[imgdir_button]/multiquote_<if condition="$show['multiquote_selected']">on<else />off</if>.gif" alt="$vbphrase[multi_quote_this_message]" border="0" id="mq_$post[postid]" /></a>
</if>
<if condition="$show['quickreply'] AND !$show['threadedmode']">
<a href="$post[replylink]" rel="nofollow" id="qr_$post[postid]" onclick="return false"><img src="$stylevar[imgdir_button]/quickreply.gif" alt="$vbphrase[quick_reply_to_this_message]" border="0" /></a>
</if>
<if condition="$show['moderated']">
<img src="$stylevar[imgdir_misc]/moderated.png" alt="$vbphrase[moderated_post]" border="0" />
</if>
<if condition="$show['deletedpost']">
<img src="$stylevar[imgdir_misc]/trashcan.png" alt="$vbphrase[deleted_post]" border="0" />
</if>
$template_hook[postbit_controls]
<!-- / controls -->
</div>
<!-- message, attachments, sig -->
</td>
</tr>
</table>
$template_hook[postbit_end]
<!-- post $post[postid] popup menu -->
<div class="vbmenu_popup" id="postmenu_$post[postid]_menu" style="display:none;">
<table cellpadding="4" cellspacing="1" border="0">
<tr>
<td class="thead">$post[username]</td>
</tr>
<if condition="$show['profile']">
<tr><td class="vbmenu_option"><a href="member.php?$session[sessionurl]u=$post[userid]">$vbphrase[view_public_profile]</a></td></tr>
</if>
<if condition="$show['pmlink']">
<tr><td class="vbmenu_option"><a href="private.php?$session[sessionurl]do=newpm&u=$post[userid]" rel="nofollow"><phrase 1="$post[username]">$vbphrase[send_private_message_to_x]</phrase></a></td></tr>
</if>
<if condition="$show['emaillink']">
<tr><td class="vbmenu_option"><a href="sendmessage.php?$session[sessionurl]do=mailmember&u=$post[userid]" rel="nofollow"><phrase 1="$post[username]">$vbphrase[send_email_to_x]</phrase></a></td></tr>
</if>
<if condition="$show['homepage']">
<tr><td class="vbmenu_option"><a href="$post[homepage]"><phrase 1="$post[username]">$vbphrase[visit_xs_homepage]</phrase></a></td></tr>
</if>
<if condition="$show['search']">
<tr><td class="vbmenu_option"><a href="search.php?$session[sessionurl]do=finduser&u=$post[userid]" rel="nofollow"><phrase 1="$post[username]">$vbphrase[find_all_posts_by_x]</phrase></a></td></tr>
</if>
<if condition="$post['userid'] AND $show['member']">
<tr><td class="vbmenu_option"><a href="profile.php?$session[sessionurl]do=addlist&userlist=buddy&u=$post[userid]"><phrase 1="$post[username]">$vbphrase[add_x_to_buddy_list]</phrase></a></td></tr>
</if>
$template_hook[postbit_user_popup]
</table>
</div>
<!-- / post $post[postid] popup menu -->