And another thing. If you have to use the newest version of RServe you will have to compile the package. On MacOS you will need the packages mentioned on the relevant R website:
https://cran.r-project.org/bin/macosx/
On a windows system you will have to compile the package with the help of RTools
https://cran.r-project.org/bin/windows/base/rw-FAQ.html#Can-I-install-packages-into-libraries-in-this-version_003f
I recently noted that at least when compiling the RServe package Rtools does not like to sit in a directory with blanks in the path name, so better have it at a place like
c:\rtools
rather then:
c\my programs\my little r collection\R-Tools