4-stamp definitive set issued in 1971. Not listed by Scott. I've always assumed this was an expanding set with more values to come however the set was issued close to the time when RAK integrated into the UAE. Note that unlike the vast majority of RAK issues, the subject matter is of primarily local interest. These are lsted by Gibbons as #78-81 but unpriced.
The cover illustrated below shows an international usage of 2 stamps from the 1971 set, plus 2 stamps from the 1964 Scott-listed set that were revalued to reflect the new currency in effect in 1966. The entire 1964 8-value definitive was revalued in 1966 due to a tanking of the Indian rupee. Not listed by Scott but listed by Gibbons as 60-67c (13 vals). One can argue that the cover below is philatelic in nature, however it did make it through the international mails.
Later in 1966 RAK prepared a set using Scott 1-8, overprinted in fils and rupees, in anticipation of yet another currency change. The new currency scheme was not adopted so the set is only footnoted in Gibbons as having uncertain status.