index finger for Button activate and Cast Ray and move

Hi, I am new... hope not to bother:

I had wonderful help with the Grabbing (finding the bugs) - now wonderful functioning.

BUT struggle the whole weekend:
How can I use the index finger (Oculust Quest Controller) to push a button.
How to cast with the index finger a ray that a) activates buttons in distance (with trigger button) b) Grab and Moves distant objects with trigger button.
I tried with VRTK but the documentation and current state dont match that made it too difficult

Thanks in advance .....Marc