I have the same meter. It took me a while to figure out how to use it properly. What I usually do is slide the disc over, and measure the light source (e.g. the sun or sky) then I compensate for whatever light my subject is in. If my subject is in the shade, I compensate about four stops.
I wouldn't worry too much about the zone system with an incident meter, as it is nearly impossible to meter the zones without a spot meter.