Rookie here has hard time with RPM's as well. Still learning. A search here on CCF (for 1964D Dime RPM) found a few references to RPM's this year. All so far show distinct separation that I do not see present here. Can you describe what you see out of the norm? Maybe because Its magnified so, but it looks like a nice bold strike with a flat shelf like indent to the east to me, but was not able to match it up to anything yet. Anything else showing on the coin?
I read there were three different style MM punches used during 64.
The Traditional "D" (like this one)
The Round bottom "D"
The Thin "D"
I'll respect Copyrighted material notice and only re-share a link from a previous post. Don't want no WEB-FED's on my case! Thanks, Doug.
http://www.richardsrooseveltreview.net/1964.htm