Permatex is good too, although perhaps overkill in this situation. It seals really well, but pretty much guarantees you'll have to tear the gasket in half to get the joint apart, then it's a PITA to clean up the surfaces for the next time.
My objection to RTV is that it can squeeze out on the inside and form a bead, which can later break off as a string and float around until it clogs something. I've seen this happen even with professionals doing the work.
Many years ago, a friend and I went to Grand Teton National Park, so he could photograph the sunrise. There is a moment when the sun just peeks over the mountains on one side, and lights up the snow caps on the other side, while the valley is still in relative darkness. Very impressive, I recommend it!
When we rolled into the valley, 2 hours before dawn, the dash thermometer read 5F. AND, the heater quit working! Brrr! The old wagon had just gotten it's 100,000 mile tune-up a few weeks before, in preparation for this trip; and the radiator shop later confirmed that it was a string of silicone plugging up the heater. (Not one of GM's better designs, on that engine the water pump had to come off to change the distributor cap.)
Unfortunately, his camera didn't work (apparently got too cold while setting up), but here's an idea of the shot he was going for: