Adding a feed to multiFEED is as easy as using FeedFinder or typing or copying a feed URL into a field on the Settings page. The hard part sometimes is finding the URL of the actual XML rather than just the subscription page or feed viewer. Some times you have to drill down several levels on the page until you find the right URL to enter into multiFEED. If you copy an URL into multiFEED but the article headlines are not downloaded (and the feed selector drop down just displays "Feed #n"), you probably didn't find the correct URL to the XML version of the feed.
Suppose you love recent American performance cars and want to stay up to date about General Motors' offerings. A Google search for "General Motors RSS" leads you to choose "GM Performance Division :: RSS News Feeds". On this page you find that GM offers three feeds, and you want to know the very latest scoops so you choose "Breaking Stories". This doesn't actually take you to the feed XML, but instead to a page where you can subscribe using several different readers. In this case you are lucky since there is a [view xml] link at the top of the page which points to the feed XML, but this is not always available. If there were no link on this page you could try going to one of the subscription pages to see if any of them will tell you correct URL to use. Let's look at the "News is Free" subscription page. Part way down you notice the familiar logo, and tapping it reveals that the URL it leads to is the real one for the feed XML.
To read a feed from Tom's Hardware in multiFEED find the "Subscribe to Tom's Hardware" box partway down the site's front page and click the RSS icon. On the RSS page you have two feeds to choose from, "Latest Articles" or "Latest News", with three subscription type choices for each. Either the RSS or XML/Atom options will work with multiFEED, but since Atom is a more robust format, you should probably choose that one. Tap the XML/Atom option then copy the URL from the address bar on the page that opens.
Many feeds URLs are long and tedious to type into multiFEED by hand. Luckily BlackBerry OS10 makes copy-paste easy. To copy a feed URL from the BlackBerry browser to multiFEED simply:
Save multiFEED settings and the new feed should be loaded and selectable on the front page. If not, check that the pasted URL is correct and that the feed server is not down.