You'll find samples including using R's source function at https://github.com/jmp75/rdotnet-onboarding. I just updated the existing code to use the latest R.NET packages.
You seem to be using a very outdated version of R.NET (EagerEvaluate is a function that has been deprecated months to years ago).
You seem to be using a very outdated version of R.NET (EagerEvaluate is a function that has been deprecated months to years ago).