The roof gasket is 1" thick when new......gets compressed to 1/2" thick when properly installed (4 hold down bolts---torqued to 40 INCH lbs---in other words 'snug')
Snug up the 4 hold down bolts.\\\\\\over tighten will cause other problems ie: distort gasket so it doesn't seal or end up blocking evap cooler drip pan drain holes so condensation ends up getting sucked in and leaks inside RV.
Roof gasket is only thing that should seal A/C unit to roof......no caulking around A/C roof pan.
Hardest part is lifting A/C unit up/out of roof opening and then resetting it back in roof opening.........make sure new gasket is set flat
