This code was inserted into the XF page for Research Notes. This will show the "Post New Thread" button if a person is logged into the site.
PHP:
<xen:if is="{$visitor.user_id}">
<a href="{xen:link '/path/to/research-notes-support.233/create-thread'}" class="callToAction"><span>{xen:phrase post_new_thread}</span></a><br /><br />
</xen:if>