In actual practice, you're going to be making taps randomly all over the surface. But if you use a proper rounded jeweler's hammer, you can try to concentrate your taps around the edges and watch the dome mushroom over if you're doing it right. I don't know it it's "correct" technique-wise, but I have gradually stumbled on a hammering technique that works for me. Holding the hammer head pretty close to the razor, I start sort of speed-tapping in a real rat-a-tat-tat motion as I slowly tilt the razor around on the back side of the pin resting on my mini-anvil to get it doming over evenly all the way around on both sides. I also keep changing the blade position to make sure it's tight at all positions, especially in the 90 and 180 degree shaving and stropping positions. Flip over and repeat until tight all over. I hope this helps.

Nice razor-don't beat it too hard!