In original RCM packaging .
Mmm I do not think that this is possible.
In 1912 , I believe, coins were shipped in bags and not individually packaged.
Are you perhaps thinking of a coin from the hoard released some years ago?
Still looking for 1912 Canadian 5 dollar gold in original RCM packaging from the 2012 sale prefer the hand selected option.
The RCM only released 1,551 1912 $5 gold coins in the 2012-2013 sale and both the 1912 $5 and $10 pieces (1,476-pieces) were sold out in a day, if I recall correctly. PCGS shows they have graded 251 of these from the hoard and NGC another 159 from the hoard for a total of 400-coins with the hoard designation combined. I'd imagine many others of these are now in NGC and PCGS holders, but without the hoard designation on the cert.