A useful bonus is that you can filter feeds according to content by entering keywords. Now click the plus symbol again to add the actual RSS link. Click the 'Subscriptions' tab, then click the 'plus' symbol to give your new feed a name.
Adding new feeds isn't exactly obvious but it's not difficult to work out either. The main window allows you to define a download folder for your torrent and a refresh rate to check for new ones.
Automatic installs itself as a preference pane on your Mac.
