I have seen both PharmD and Pharm.D. used. ACPE website has PharmD, and since they created the moniker anyways, I would go with that. That's also what most people's business cards say. I automatically write and type Pharm.D. most of the time, though (because that's what my school used). And if 2 million lemmings cannot be wrong, Google gives 438,000 hits for Pharm.D. and only 173,000 for PharmD 😀