Slide In Plugin Interfering with RSS feed

I installed the slide in plugin on http://www.foreverfitnessorlando.com and the rss feed became corrupt. I found out what was causing it when I submitted the feed to feedburner and gave me the slide in code. It rendered the xml feed not valid. Since I deactivated the slide in plugin, the rss feed is working normal again and I am able to submit to feedburner.