Location: Cincinnati, Ohio
The amount used per square foot will vary, possibly a lot, depending on the application method you use, how much remains in the mixing container and the mixing device, how absorptive the substrate is, and how thick a layer of glue is left on the substrate.
My suggestion is to get an initial gallon of resin, an appropriate amount of powder and blocker, sample veneer the same as you intend to use, and substrate you intend to use, and experiment, keeping data as you go. when I did a number of small stands, I would record by weight the container, resin, powder, "dry" weight of the 3", 4", or 9" foam roller, the "wet" weight of the roller after the glue was applied, the remaining weight of the mixing container and remaining mixed glue. I always estimated how much to mix, and added I think 10% because I felt it much more desirable to have some excess than not enough, and I allowed for a certain amount for a zip lock bag to judge when the glue had set sufficiently that the heating pad in winter could be unplugged and the vacuum pump turned off.
I applied a layer of glue so that when dragging my finger through it a small ridge was left on each side, but how much of a ridge is a judgement made by each person.
Unfortunately, experimenting before the first few veneering projects or a veneer species not used before is a cost of doing business, like ordering extra substrate and veneer to allow for cutting errors, veneer splits and other defects, and so on.