That's above my experience level to deliver an EVAP small leak diagnostic class.
I imagine it commonly comes down to the gas cap or the N80 purge valve.

For our engines, we have:

P0442 Evaporative Emission System Leak Detected (small leak)
Time for pressure drop < 1.55 - 1.75 Sec.

P0455 Evaporative Emission System Leak Detected (gross leak/no flow)
Time for pressure drop < 0.95 Sec.

P0456 Evaporative Emission System Leak Detected (very small leak)
Time for pressure drop < 4.5 - 6.0 Sec.

The EVAP system is covered in the Fuel Supply System repair manual.

I imagine there's a test you can manually initiate through VCDS, but I have no idea what/where it is, presumably under output tests. So if I wanted to guess if it was at the N80, I'd disconnect the N80 and plug that line which goes to the N80 then run the test. See if it now says no leak.

It's not a DTC I've had to personally resolve, so just speculation on how I'd approach it if it came up. If you do try to use a smoke test, make sure it's a low pressure smoke delivery, not more than 1 or 2 psi, or you're going to end up with a P0455. :-)