Dunlkop GCB80

Dont know this.
However it is a volume pedal. It will work as a normal volume pedal in a loop.
If you want to use it as an expression pedal, you would have to deal with an "adapter" cable, that transfers both conections of the peadl to an trs output.
Still than, if you get such a cable, you will have to deal with the fact, that volume pedals - in general (not sure about this model) - use logarithmic potis, expression pedals - in general - linear potis.
Thus, I wont recommend this pedal as an expression pedal for the kemper.