I would like to configure separate RSS feeds for two different subforum categories. One for the main forum, which excludes the foobar2000 subforum, and one for the foobar2000 subforum itself. Currently, there is only one RSS feed, and it includes the entire site, and is limited to a global configured number of recent topics.
Have you seen this? ElkArte is based on SMF, so all of these params should work:
http://www.simplemachines.org/community/index.php?topic=25009.0