The query RSS feed web part can be used to create a feed based on a custom query entered in the web part properties. It uses a built-in query data source as a source of the feed data. It displays a link leading to the feed, which is located at the URL of the page where the web part is placed, with a querystring parameter appended.
Help URL: http://devnet.kentico.com/docs/webparts/index.html?QueryRSSFeed_overview.htm