Somehow I didn't notice earlier that this record is listed as 12" - it's actually a 10" disc. And, if you look at the matrix info on DAHR it states "Master size - 10 in." The 12" designation here is a mistake.
Not a single R-prefix record is listed in the 1916 Talking Machine World either. But there is a special picture ad for this particular record in a Canadian newspaper, the Medicine Hat News (Medicine Hat, Alb.), February 19, 1916, page 2.
I have turned this back to being a Canadian record because of the prefix. The content in support of the British, Canadians, and their allies in World War I also supports a primarily Canadian target audience.
Stuart was released on the A-series too, though, so he was definitely not considered of exclusively Canadian interest, and that's what the U.S. and Canadian prices indicate.
I love, by the way, how Steven Barr characterizes the content of the R-series:
"As with R-4000 series, the majority of the issued material is of minimal interest to all but the most dedicated musical masochist, with the exception of sides by Joe Hayman (of "Cohen" fame) and Billy Williams."
Steven C. Barr writes that the masters for this series were recorded in both the US and UK, and likely were only intended for release in Canada. The label shows both US and Canadian prices and doesn't have the "...shall not be re-sold in Canada..." rim text, though.