As far as I know Rokinon does not make any cine lenses compatible with micro 4/3. What you have is probably a standard 4/3 mount, which is different than micro 4/3.

I use the exact same lens a lot, but the Canon mount version. If you get this 4/3 to micro 4/3 adapter it will work on your GH4 just fine:

http://www.amazon.com/Neewer%C2%AE-Plastic-bayonet-Adapter-Panasonic/dp/B00CHZ44SA/ref=sr_1_1?s=electronics&ie=UTF8&qid=1417759880&sr=1-1&keywords=4+3+to+micro+4+3+adapter