In a log cabin, there's that space between 2 logs as they curve together (unless planed flat). This would be filled in with clay and straw chinking, to fill in and smooth out that curved gap. I think of using R as a way to 'chink' the last/first hours of long acting insulin doses where the glucose curve wears off steeply.
One important point is to start with a tiny dose (0.25 units) and curve it over the 4 hours it works, so you see how your cat responds. You start about 2 hours (or when you think it'll work best) before the regularl insulin pre-shot, test, give the supplemental R, and test each hour until the R should have worn off (about 4 hours). With experience and testing, you may identify an optimal time to give the R. Give the regular dose at its scheduled time if the pre-shot allows and continue hourly testing. Be prepared and have your hypo kit ready, as this is an experiment and you don't know how it will work out.
You might read over some of the posts and spreadsheets in the acromegaly forum for examples of how they used R.