Normally H. D. Smith marked the shank of the screwdriver with their logo inside a rectangle that was applied at an angle to the shank. The Irwin's I have seen are also marked on the shank. Some that I've seen also have a number forged into the tip, actually just in back of the actual tip.
The German and Italian ones are usually marked where the shank starts to flare out to make the seat for the scales. Not sure what you call that part of the SD. Most of the small SD's are made in Germany, I have yet to see a small H. D. Smith made one.
Mike