here's a method that's free:

Save one file on the 7k (anything - eg initial condition) on a blank SD anywhere in the first folder.
Transfer to pc, follow the path Private, Technics, Kn7000, erase the inf and bak files there.
Open Tfld001 erase the contents.
If you want any more folders, you can create Tfld002, 003, etc etc now.
Copy your previous contents into each folder following the normal numbering convention, eg if they are floppy disks the contents are already 1-10 or 1-20 without numbering duplications.
Transfer to 7k, each folder will show its contents with the floppy file names ready for load.
Once you save anything on the 7k this method can no longer be used.

You can buy programs like SDExplorer to make an sd structure which work reasonably well with easier renaming etc and copy/delete/transfer on existing saved cards, but for a blank card this gets you going.