First of all you have to convert the .cvs file into a text file where all the lines before the datas have to be initiated by a "!", since they are comments.
Then add the line #HZ S MA R 50
that means: frequency in Hz, S paramenters, representation Magnitude&Angle, Impedance 50 ohms.
Then add the data lines composed by 9 columns that is frequency + 8 columns of Sxx datas
the data betwwen two columns have to be separated by space ot tab.
have a look to this:
https://edadocs.software.keysight.com/display/genesys2010/Touchstone+Format