Probably good advice. I would question if the OP really wants to purchase this coin when a much more attractive certified example might be found with a little bit of searching.
It's already been mentioned about the lack of wear on the MM, but I feel the same way about the date. It's way to "clean" for the amount of wear the rest of the coin exhibits. Also, from your Dino Lite pictures, I don't like the area immediately surrounding the MM. It looks odd, like it's residue from an adhesive.
Fake! Also, does anyone else see the outline of the S mintmark that was removed to add the D? Ah, I see the person who replied above me saw it.
It's hard to say because it this a flat view and you cannot get a good view of the sides of the mint mark. The scan makes it kinda look like it was worked around the mint mark. You really have to look at the sides.
It does kind of look like there's an S under the D, but why would anyone start with a 1916-S instead of a 1916-P? I don't see an "apex" to the right of the "triangle" inside the D; in other photos I've seen of worn examples, it was very clear. I also agree that the MM isn't nearly worn enough to match the rest of the reverse, and that the closeups show what appears to be work behind it.
Has the OP looked at the four mm positions which are described in this thread: https://www.cointalk.com/threads/data-1916-d-test-your-authentication-powers.101697/ ??? Only one mm location is high like the OP. A high mm would need to be the mm found on die #1. Does it look like the OP's mm? I would pass on this coin.
I saw the "S" screaming at me. They used the S as a position indicator. Plus the S gave the wear a natural well shape to give the appearance of a natural MM. A 1916-P would not have that protected well.
I gotta with fake. Every authentic 1916-D in that condition I've ever seen has the mint mark worn down significantly more than this.
No real (to me). Looks like there's flux behind that "D" to me. Yeah, and we need to check on the correct shape of the MM and serifs.
If that dime is real, it will be a miracle. I haven't seen a miracle happen here for a while, in fact I don't think I've ever seen a miracle here. Show me the money!
There is a defined border around the mint mark, suspicious. Unless the punch had the exact same dimensions (a rectangle). If the punch had a head shaped like that rectangle, then it was engraved crooked (not aligned with the rectangle's sides), and the engraver of the punch would not have done that. I agree that an S stood underneath. Case closed. HEY, but nice photography!! Again, good photography solves another case.
Looks like a real dime, not imaginary, but that D is not right, so it is bogus. I have a G4 that is considerably nicer and its D is much more worn.