Not a rife... and its not really a Ketland either. A Belgian-made "fake" Ketland ca. 1816-1820 with fake British proof marks. Having said that, it is old and its "fake" only in that it isn't English made. Beginning around 1816... after Thomas K Jr. returned to England, there seems to have been a rash of "Ketland" marked guns imported... there was no "truth in advertising" law at the time and the K name was extremely well known so it was common, if not exactly ethical, to put any name you'd like on them. Thirty years later the Belgians were selling all sorts of double guns marked "Manton" or "Richards"...
The large typeface of the name, stamped in an arc is a dead give-away, even without the funny proof marks.