Here is how to do it:
The Default action is UP/DOWN by Selected View in Browser Mode.
In Browser Mode, select "Favorites" as your View.
Use Rig Manager to make the two Rigs you will be using your ONLY two "Favorite" rigs.
The Dual Foot switch will switch from one rig to the other. In fact, with a range of only two rigs, it will switch from one to the other, even if you accidentally press the wrong button 
IMPORTANT NOTE: To ensure these rigs remain as your only two favorites:
In System, UN-check the "Auto-Favorite" Box.
.
In Performance Mode, it may be even easier:
The default action of a Dual Footswitch in Performance Mode is to ONLY access the activated Performance Slots.
So, Have JUST ONE Performance in your Kemper, with just two slots in the Performance.
... And this says it all I guess 
You're welcome
Select a Performance Slot.
Un-check "Slot Enabled"
SAVE the Performance.
