That one in the picture looks good to me. Assuming the ones you replaced were installed correctly, just match the depth that they were. If like me, you didn't take notice before you pulled them, just set the new seal outer face depth to just at/past the tapered machined part in the cylinder head, like in your picture. Of course make sure the seal is straight to the bore/parallel to the outer front surface of the hole in the head.
The only warnings I've read are if you drive it in too far, it pops out the back, then the valve cover gets to come off and the fun begins. I didn't use the special tool either, just the piece of pipe and the ol' eyesight, yep, that looks pretty good...button 'er up.