Yes however, my understanding is it calculates area after you know PR. I wanted to figure out if PR could be figured out just using the water meter, but appears I need area which I don’t know how to determine.

That’s correct. Think about dumping out 1 gallon of water in a small pot. The water will travel many inches deep. If you sprinkle the same gallon of water all around your yard it will clearly stay very near the surface. By just knowing the water used and not how it is dispersed, you don’t have enough information to know how deep it travels.

I made the drip calculator linked to above such that you can use the description to come up with a target for total number of gallons you want to deliver at it’s destination, then set up the controller to deliver exactly that amount.