Measuring VTF with electronic gauge....

It depends on the gauge, but most of the decent ones designed to be placed right on the platter and the pad for the stylus designed to be on the same level as the record top surface.

The situation with some cheap Chinese gauges is different if they are not designed for measuring cartridge VTF.

I want to admit that I put my Ortofon digital gauge on my metal (or graphite) mats. So it’s not exactly the platter, because I do not remove the mats, but i definitely remove the record :))