Not sure how much this relates to a leatherworking issue, but, I spent 35 years hand crafting fine furniture, cabinetry and accessories. I always signed my work in a discreet location. As proud as I am of what I created, my work spoke for itself. but then again, it was not for sale on Ebay. Put it on the back in really big letters (be proud,it's fine work) and word of mouth will bring you business.
Edit: for all you saddle makers. You guys are at the level we all (well at least me) wish we could achieve, but... how many people would turn a saddle over looking for a makers mark? Beans and Oranges.