I changed this function to return an empty string if onimod_rss=="NO" so that it doesn't return "undefined" and add that after the subject in the main topic post
function _doTopicRSSLink(id) {
if (onimod_rss=="YES")<br/>
{<br/>
return '<A HREF="/'+onimod_webdbname+'/rssfeed.xml?OpenPage&MainId='+id+'" alt="'+text_rsstopic+'" title="'+text_rsstopic+'"><img src="rss.gif" border=0></a>';<br/>
}<br/>
else<br/>
return '';<br/>
}