i am also on a ryzen system.
when you install manjaro 17.0.1 or later using kernel 4.9 installation should work fine on ryzen. at least it did for me. it shows a couple of errors during boot, but it should boot fine.
one thing to remember on ryzen systems: you have to update your motherboard firmware to the latest version!
i recommend to do that before installation.
if you want to check out the latest release of manjaro (attention, this is NOT finished), download from here: