Don't use sealer unless there is some issue with the oil pan.
The sealer will actually eat into the sealing ribs of the molded windage tray gasket. It will still seal, but if you ever remove the tray, the sealing ribs where the sealer was will look like they were mixed into the RTV sealer.
I have a used windage tray like that, I should take a photo of it.
I also widen the windage slots a bit.