The distance is between your middle finger and your thumb. With the hand stretched out as far as it will go.
Say start at the pressure point at the hinge of the jaw, behind the ear. (that's a good one, even muscular dudes feel that one.) Put your middle finger on it till you feel pressure(or your partner is easier) then while keeping the middle finger there move the thumb to the front of the throat (should be at the indention of the esophogas (however you spell it) that's a common one, with the thumb.
Then let go of the point at the jaw with the middle finger keeping the thumb at the hollow of the throat and "swivil" the hand around the side of the neck to the shoulder (where the tip of the shoulder attaches to the arm) and push with middle finger. Should be a point there. Or to the side of the neck and upper shoulder where the neck attaches to the shoulder, should be one around there. (There's a couple at the clavicle too. That's one he showed me, brings you straight down to your knees, ouch!)
You can keep "swiviling" the hand like this all over the body from wherever you wish to start. It's easier for me starting on the back of a person (good way to find where they're having tension and pain with a back massage.)
You can walk the hand up and down the body like this, from the feet/legs/ankles/ all the way up to the head.
-On a weird side note, (pun intended lol) it reminds me of a little "jazz improve" cheat my old saxaphone teacher taught us back in the day. Stating that no matter what key any song is in and your jamin' doing your solo and play a wrong note, you only have to move a half-step up or down to be back in key (in tune) with the rest of the band.
Is the universe truely this simple?
It is easier to show, much like jazz improve.