How to test the aftertouch?

I bought a Studiologic SL88 Grand and I've been playing around in Kontakt and Studio One 4 but for the life of me, I still haven't been able to find how to apply aftertouch to a mod or knob - like say, for example, reverb when you use the aftertouch -, I've tried a couple of tutorials on how to assign it but I haven't found it to respond. Now I'm worried if I got one of those sl88 with issues in the keybed.

How would you easily test if the aftertouch is working at all?