I already threw the box out, but I'll look it up to verify. The slot I'm using is rounded so it's probably correct. For what it's worth, it's a comp cams set, do they use cloyes sprockets maybe?
You need to go by whoever made the thing. The key should fit ANY and ALL of the slots...that is what they are for. It might be there is a machining burr in one of the slots, etc
There are always three symbols of "some sort." Say, a "0" a triangle or diamond, and a square. the square timing mark must be used with the square marked slot, the diamond goes with the diamond, and so on. With the thing properly set up, the key should be close to 1-2 O'clock with the marks properly lined up
When putting the distributor back in, remember that "the marks" are NOT no1 ready to fire, but instead no6 ready to fire. Either time the engine with rotor pointing to no6 hole, or else rotate the crank one turn and then set it up
