If anyone needed.

Add this code:

<!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_default_style ">
<a class="addthis_button_preferred_1"></a>
<a class="addthis_button_preferred_2"></a>
<a class="addthis_button_preferred_3"></a>
<a class="addthis_button_preferred_4"></a>
<a class="addthis_button_compact"></a>
<a class="addthis_counter addthis_bubble_style"></a>
</div>
<script type="text/javascript" src="//s7.addthis.com/js/300/addthis_widget.js#pubid=xa-527d10201fa981e8"></script>
<!-- AddThis Button END -->

in /themes/default/subtemplates/entry.inc.tpl

Before:
<p class="left"><strong>{#complete_thread_marking#}</strong></p><p class="right">

And in /themes/default/subtemplates/thread.inc.tpl

Before:
{if $settings.rss_feed==1}<div class="small" style="text-align:right;">

Demo: http://grchat.com