When you assemble, coat both mating surfaces with RTV and mount with the bolts just beyond finger tight. Wait 2 hours and then tighten down to correct spec (wont be much).
You do not need much RTV to form the gasket. Excessive squeeze-out breaking off inside the housing and causing chaos with pressurized oil systems is why a number of mechanics do not like it. You just need a layer just thick enough that you cannot see the metal beneath. There should only be a minimal amount of squeeze-out if you did it right.
Surface preparation helps as well. I wire brush or scrape the surface clean of crusty stuff (down to bright metal if necessary), and wipe the surface with a little bit of brake cleaner before I apply the RTV.
