Once you've set up your rental property in the Rental Properties and Royalties tab, you'll be on the "Rental Summary" screen, where you'll see headings for Property Profile, Rental Income, Expenses, etc. Click on Expenses, then continue thru the Enter Common Expenses screen and you'll find the entry screen for Report Mortgage Interest.
Look below the area for Lender Name & Interest Paid and you'll see a small box entitled I also paid mortgage insurance on my Form 1098. Put a check mark in this box and a small window will open showing an entry box for Qualified Mortgage Insurance Premiums. This is where you'll make your entry.