trunk seal

Does anybody have any suggestions for installing a trunk seal for '66 f-lane? Just bought a seal from mac's and just installed it, now when I try to shut the lid it is about a quarter inch to high and the latch won't catch. Do I need to close the lid as far as it will go and lay something heavy on it to compress it for a day or do something different. Any info will help a brotha out big time , thanks in advanced.