I think it may vary by the mask, kit and what needs masking. The mask for my 1/48 P-51B included masks for all of the canopy glass, one or two other clear bits (which I didn't use since they're pieces that can be installed at the very end), and the landing gear wheels.
You may want to check their website and see if the mask you're looking at has instructions. I know I was able to view the instructions for the Dauntless mask I ordered right from the product page. It works a bit differently...providing just outlines for some of the canopy frames and requiring you to mask the bigger open sections yourself. Which may be the case with your F-4...
On the Bench: 1/32 Trumpeter P-47 | 1/32 Hasegawa Bf 109G | 1/144 Eduard MiG-21MF x2
On Deck: 1/350 HMS Dreadnought
Blog/Completed Builds: doogsmodels.com