You don't want a pure Ruderalis - there's no usable THC in that breed.

Look for an autoflowering hybrid.

There's always a tradeoff when you add Ruderalis to a mix - to get that autoflowering capability, you lose a little power, a little yield, and probably a little flavour.
However, some of the newer ones are being marketed as high THC autos.

Here are a few to check out -

This from Bomb Seeds - Auto Bomb is supposed to have 15% THC - Auto Bomb Feminized | Get An Explosive Autoflowering Strain Now!

We sell out of this one all the time - supposed to more than 15% - Feminized Seeds Blue Treacle Auto - Blue Treacle Automatic Feminized

This is Advanced Female Seeds new Auto AK-47 - it's supposed to be good - Automatic AK Female | This Potent AK-47 Defines High-Caliber Weed

This is a Big Buddha Automatic - most people love his stuff - Big Buddha's AUTOMATIC

We have a ton of auto's on our site - just depends on what you're looking for.