I rewrote the Touchstone import from scratch. It supports (DB, MA, RI) (G, M, K and Hz) formats. It should handle both S1P and S2P automatically. It checks for the frequency to increase and no tokens after any data is found. Comments are allowed throughout the file. The software expects at least one space (0x20) to be used as a delimiter. Some files will used more than one space. Others will end the line with a space. The software handles these cases as well.
I had discovered AppCAD actually has support for stability circles. When I tried to feed it a TS file from the Youtube example, I also learned that it requires at least two data points. So, I replicated the dataset and increased the frequency. (see attached TS file).
While testing, I also found that my last software has a MAJOR bug with the stability circles. When I went from my test code to the actual subroutine, I screwed up the math. So, both of those versions are wrong!
The software now exports Touchstone files with the decimal point. It also expects the decimal to be used on any files you import. Attached shows the original test code, AppCAD, RF Assistant and my latest 2.06 software showing the attached Touchstone file.
If you have Touchstone files you would like to try as test cases, go ahead and upload them and I can run them through.