An OPML file can contain multiple RSS feed urls in xml format, these files can make super easy to move your RSS subscriptions between your RSS applications.
NewsFeed Launcher also supports the OPML file format, so these files can be easily imported.
This article describes, how you can search a RSS URL of a website, what you can use in the NewsFeed Launcher or other RSS reader application.
Most of the time you need to search a page in your web browser (Chrome, Firefox etc.), where you can see similar structure as the following examples: