I have tried using,
with open(myfile.rtf, 'a') as file:
file.write("{\rtf1\ansi{\fonttbl\f0\fswiss Helvetica;}\f0\pard")
file.write(my_String_here)
file.write("\par}")
I have briefly looked at PyRTF but wasn't able to find an example that works with Python3
Your problem is probably that \r
and similar characters are treated as escape characters. Use raw strigns instead, eg write(r'{\rtf1....')