Measuring VTF with electronic gauge....

Straight on platter!

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.

Thanks that's what I thought. I'm using a Winds ALM-01

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 :))

What matters is that VTF be measured with the stylus at the same level as when playing a record. Some arms because of their design can cause VTF to change as the angle of the arm changes. So in other words you want a gauge that works like chakster said, with the stylus at LP level. Not LP level plus the gauge. LP level.   

VTF btw is always specified as a range. Anything within that range is perfectly acceptable. Within that range however VTF is set by ear. If you like it at the high end of the range then that is the "correct" VTF for you. Precision therefore is only a factor to the extent it keeps your "by ear" setting from being too high or low.