All GPU features in After Effects except for one will just work automatically with that GPU. The one exception is a feature that you very likely don't and shouldn't care about: the ray-traced 3D renderer, which is only narrowly useful and for which there are superior alternatives for working with 3D in After Effects.
Details about GPU usage in After Effects are here:
That's because AMD cards don't have CUDA. CUDA is NVIDIA-only technology.
However, unless you are using the obsolete ray-traced renderer, that GPU acceleration is meaningless. AE only uses the GPU to accelerate the ray-traced renderer. Now, some third-party effects (such as Red Giant Universe and Element 3d) do make use of the GPU, but they don't require that box to be checked, nor do they require CUDA.
If you don't believe me about AE's lack of GPU use, believe Adobe: GPU (CUDA, OpenGL) features in After Effects
And, if you were planning to use the ray-traced renderer, here's a better suggestion for your system: use Cinema 4d. It comes with AE CC! Details of CINEMA 4D integration with After Effects CC
Edit: for some reason, I didn't see Todd's reply when I went to post this. Oh well. Weird forum software and my weird network don't seem to get along!