Doesn't look like one is available at the moment.
I did a view-source:
http://www.crossfit.com/ in Chrome and the only RSS that came back was
http://www.crossfit.com/rss. However, adding that link in any RSS reader returns nothing.
Also, the RSS reader extension in Chrome doesn't find anything either when searching the
http://www.crossfit.com/ site. Hopefully it will be fixed soon, as I'm pretty sure apps like BTWB use the RSS feed to update.