Question about a 1966 hi numbeer 564 card
 

I recently purchased a blank back proof card of Bob Chance from the 1966 Topps set. His card is a hi number card #564.

My question is; on the front of the card in black marker is a line and the letter R. The seller noted that this card is marked by the editor. Is that correct, did the editor mark proof cards in such a manner? thanks for your answer and comments.

FYI: You gotta post a picture of it, so people can see and know what you're specifically asking about.

I have tried many things to attach a photo, but no luck

https://www.ebay.com/itm/134704749050 - this should take you to a photo of the card.

Here are the pics from the listing...

Attachment 632998


(So you know, this thread is also in the wrong section.)

The writing could be from anyone other than Topps, but my guess it was written by Topps …who writes R1 on a card anyway? I have some proof items from Topps and it looks the same , if that makes any sense.
Scott