I assume (?) that the R Method is using (?) the Circle Least Squares Fit classic algo. Google that in order to understand the whole approach.
I have various C#'s that do that … but that is rather irrelevant (I guess) since it appears that you are not familiar with coding.
Plus (various similar threads around):
Plus 2 classics (rather skip these):
LSBF_0301001.pdf (638.6 KB)
LSBF_gander.pdf (277.7 KB)