Enabling GPU in Artlantis (or other rendering/design programs)

Hi, it occured to me that this problem is not handled properly throughout the internet. I want to use my dual-970 setup's full potencial, but now if i start rendering an image, my 4790K is working hard on 100% and my lazy GPU-s are lying around, doing nothing.

I added the .exe in the nvidia control panel, so theoretically it should be working, but it's not. What did I miss? How is this done, and what are the best solutions? Which program can handle GPU-rendering the best?