Hey, I use that same foot switch, and it should work fine with the H9 assuming its connected with a stereo cable. In H9 Control you'll need to click on the Pedal button in the bottom right hand corner of the app to get to pedal settings and configure the EXP jack to expect an aux switch instead of an expression pedal. Then, you can go to Aux Switch Mappings to start assigning the switches to particular functions on the H9; it should be pretty self explanatory.
