hi all,how can I get a RSS link to all the items inside a category?

In a catalog website (k2 content) I have a product category which has a lot of subcategories with items in those subcategories.... I want to get a link to subscribe to the RSS feed of all the items below the product tree.

I tried enabling the 'show RSS link' in the k2 product category preferences but since I only want to view subcategories onscreen (not showing items until bottom level category) when pushing the main product category RSS link, I get no items.

any ideas would be really appreciated! =)