Over the years I have submitted various RSS feeds to Google in order to supplement my main sitemap files, giving faster updates to GWT of new content. (At least that was the thought/my intention... I am not sure if it really worked).
While GWT is still reading my current RSS feeds, I now see that RSS is not an option for new feeds, only the following:
General Web Sitemap Mobile Sitemap Code Search Sitemap Geo Sitemap Video Sitemap