On mine the DF is on the lower left of the inside/backside. If you look at the circle swirl, just below it, you can barely see it, but I'm pretty sure that's the DF. They are kind of smudged up on this stove but they are there.
Jim, that area you reference is initials. So somebody put their initials on the pattern or maybe did it for this one time pour.
Also the ash pay sure does look to be in excellent shape. Usually, or at least the ones I have seen, are more beat up from use. Used but not abused I should say.