RSS/Atom feeds are automatically published as meta tags. If you don't see the actual feed icon though, that's because your override does not support it OR you simply have that feature off in the menu or category's options.

In any case, just append ?format=feed or &format=feed (if you already have a ? in your current URL) and you'll get the relevant feed from K2. Or just switch to view-source to see the relevant feed links.