"RPK" overprints is an interesting and challenging area in post 1979 Cambodian philately. Basic and yet valuable information regarding the status of "RPK" overprints is available in CIP #64, this blog entry is to offer a comprehensive list of basic stamps of the "RPK" overprints.
Although veteran postal staffs have confirmed that the overprints did see commercial use in 1979/1980, the number of stamps officially overprinted "RPK" is uncertain, what now available to collectors is based on observation. A total of 40 stamps and 1 souvenir sheet are recorded so far, here they are quoted in Michel catalogue numbers and the overprint ink colour is stated. Your input is welcome to benefit all interested collectors and please stay alarm that forgeries exist (one update left out in the table below, Sc #253).
(click to enlarge)