I have a 15hp Kohler ProCommand, single cylinder engine. It takes 1 1/2 qt (32 oz + 16 oz).
Most likely, your engine is the same, so try 1 1/4 qt, check, then add to "F" on dipstick as needed. I find I cannot read the dipstick after pouring in the oil, but need to run it, then let it sit for a few minutes, and then check. When pulling the dipstick right after pouring in the oil, the sides of the tube are covered and will obscure the reading.