An image from one of my articles has been posted online in some discussions, with attribution of the underlying image, but it includes some changes / annotations.
I think that this is a better image.
The difference is in the two pin assembly at lower centre, an addition to my original image. My recommendation is that the DUT is attached to the same side of the pin strip as was used for the calibration parts, as shown. Though I did not intend that this jig be used much above 100MHz, small details like this might improve its accuracy.
Successful measurement with VNAs is very much about the fixture.
The clip leads don't make a very good fixture at HF.
PS: I have not held the callsign VK1OD for many years, but I still am known as Owen Duffy.