Correct configuration of the Zebra GK420d for PostNL labels

Symptom: label is not printed correctly, but as shown in the example below: 

Install Zebra Setup Utilities.

https://www.zebra.com/us/en/support-downloads/printer-software/printer-setup-utilities.html

Select 'Configure printer settings'.

For the correct size (for PostNL label 102 x 150mm) and select 'Finish'.

Now select 'Open printer tools' -> Action -> Calibrate media (2 to 5 labels will be printed)

The tool can now be closed and the label printing should work correctly.