TrueCoach's workout builder makes creating a superset of multiple exercises super easy.
Simply add multiple exercises and click the "+Superset" button between the exercises you want included in the super set.
There is also a handy time-saving keyboard shortcut for supersetting...you can hit COMMAND + SHIFT + K to superset the current exercise with the previous one.
(Note: If you are on a PC, the shortcut is CONTROL + SHIFT + K)
Once multiple exercises have been linked in a super set they will display as "A1,A2" or "B1,B2,B3" etc.
You'll see Dumbbell Row and Reverse Lunges supersetted in the iOS app below: