Thought I had Scotch on the shelf. Oh well... For those wanting to try a substitute for it, I first tried this with Willett 4-yr Rye and it was not appealing. Laphroaig 10 was interesting though, in that it tasted like one of their Cairdeas port barrel aged expressions, sort of.
Too much scotch - I think I will drop the scotch to 2 oz (or maybe 1 1/2), to bring in line with the classic ratios of a Rob Roy. May also add another dash of bitters.