This is probably now apparent to the OP, but just in case it isn't ....
To me, the Zone System is a method used to determine the development of your film.
If you are not shooting individual sheets, or multiple film backs (N, N +1, N -1, etc.), or different bodies for different lighting contrasts than it really isn't the Zone system you are using.
I think the OP is really just trying to figure out how to best use a spot meter with roll film.