"ottersea"....."Pirate" posted a good photo of the difference between the butyl tape and rolled caulking. Rolled caulking was the standard years ago, but always oozed, got dirty and look like heck. The black butyl is now the standard. I single layer will work fine. I would install the tape carefully on the window frame and then insert the window back into the opening. When you reinstall the interior frame, tighten it incrementally in an "X" pattern so you don't squeeze down one side all at once.
Once you're done, get some pure silicone (clear) in a tube and run a bead along the top of the window and down both sides about 6". Make sure the surface is clean.