totally agree with puppet, deck down on a regular roof rack is the way to go. Honestly, the factory cross bars on your forester should do it. You can either get pipe insulation or buy some pads, which I think holds the yak in place better on the top.
That's what I have been doing now for 6 years and it's worked great.
TDF's suggestion is probably the way to go if your kayak is just too heavy to lift up on the roof deck down (which his is!) but you can also get something like this to assist in loading:
http://www.llbean.com/llb/shop/41137...id=34644939177
I haven't tried putting two yaks on top of my car, but you could lean one up against the other as puppet said. If you are going to be transporting two kayaks very regularly, you may want to either invest in a trailer or get j racks.