I’ve got the Metabo and it’s crosscut rail. It will fit a regular festool track. I don’t know about the FSK. Let me know if you want a picture of the base. Maybe that will tell you something.
I would also be interested in the potential inter-operability of the Festool and the Metabo FSK tracks. Could not find anything so far and have not been willing to do the legwork of experimenting myself. [emoji23]