You take a DD Floppy disk (720K) and format it on a PC, or take HD floppy disk (1.4Mb) and format it to 720Kb. Copy the Ami software to the 720Kb formatted disk, AFAIL it should fit as it was designed to be done this way.
Don't forget that HD floppies have two square holes on either side of the disk. One is for write protect, the other is letting the drive know it is an HD floppy. To get the PC to format a 1.44MB floppy at 720KB, you must put an opaque piece of tape over the hole on the left hand side (with lable facing you). If not, it will always format at 1.44MB.