Looking at my WFR in the crinkle finish with a motor, it doesn't look like there is any place to attach a hand crank. These do still have a spoked wheel, but I'm not sure how you'd retrofit a hand crank to it. The motor attaches to the back of the machine with screws. There is nothing like a "motor boss" as on the ends of most Singer machines.
The only one I've seen is here:
White FR hand crank pic.
I read somewhere (can't remember where) that White's were sold in the US, so not as many were made with hand cranks, mostly treadles and motorized versions.