repairing crank seal

Im about to install my crank seal from the outside. Turns out Felpro makes the same seal size as the factory one. Its made of nitrile like the factory one, but what i think is better is irs double lipped where the factory one is not. My question is What type of silicone should i use on the outside on the seal between the seal and the crankcase. Also does siliconing the back of the belt housing hurt the seal? Or is it possible to over tighten the belt back plate?