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.