If possible, the sitemap should be generated automatically using say your site's feed as one source, along with other webpages on your site mashed in - for example your about pages. As an alternative, you can have a top level sitemap that links to other sitemaps (link) - and one of the linked files could be the syndicated feed. This can be a very effective solution, since there is little manual work needed (as the syndicated feed is generally auto created from a cache or the data store)..

Also note that with RSS, you will not be able to specify Google or other search engines, properties such as priority and changefreq, which serve as important hints to the crawler system.

Vishal Shah