Replacing Fantastic-Vent Seal

Hey, I am replacing the seal on our Fantastic-Vent (now acquired by Dometic). I ordered the new seal, I got up on roof to replace and found that the original seal was held in place with some type of adhesive. The replacement seal does not have a peel-n-stick adhesive or anything. Should I use some type of contact cement or adhesive? What type? Or just replace the seal?

Happy Thanksgiving!! Thanks....