The script is designed to work like the FilletSrf command (by picking two surfaces). To set the radius you just type the number you want into the command line at any point before you pick the second surface.
You can create an alias or run the script from a button that you create.
The original version of the script can be found here . The original version just makes the raw fillets. You have to do all the trimming and joining.
You can download this 3dm file to get some examples to practice with:
fillsrf_examples.3dm (1.0 MB)
You can find a nice explanation of how to run the script from a button here.
The most recent version of the script can be found here
I think that is the version that you have. It makes the fillets and does the trimming and joining when that’s possible.
you can run that script from a button or alias using this macro:
-_RunPythonScript “[path] Filsrf_JoinV2.py”
You need to replace [path] with the directory location where the script is saved.