I was also surprised to find out there is no oil pan gasket.
I used RTV using the method, that YouTuber, Chris Fix describes. Basically, it's a stepped process, put the RTV on the sump plate, let it setup a bit, install the plate with just enough tightening to squeeze the RTV, let it cure a bit longer, and then tighten down.
This method worked really well for me. No leaks.
Here's a link to his video:
http://youtu.be/21CvanhKILA