Feed Search looks for feeds and OPML in the page you are currently viewing.
Feeds will most likely be found when the feed icon

is displayed in the URL bar.
It will
only find feeds and OPML that are identified with the correct mime types. i.e. application/rss+xml, application/atom+xml and/or text/x-opml.
To
add found feeds, drag them onto the category/feed tree.
To
Quick View found feeds, drag them onto the Items Pane.
To
add found OPML, double-click it.