If it looks exactly like the picture, you will have to replace the entire D seal that is attached to the H seal . My Coachmen had a D seal that locked onto the H seal and was separate and replaceable.
That is going to be a pain in the ***** to replace. You will see it has sealant holding it to the exterior and staples holding it on inside. You will need to remove the interior staples and and exterior sealant before you can remove the seal.
I would gladly pay a service center $300 - $400 for that repair.
2017 Salem Villa Estate 395RET-
2011 Coachmen Freedom Express 295RLDS- Sold
2015 F-250 FX4