It depends on the camera design. For instance, Graflok
backs depend on the fresnel for spacing of the ground glass.
The reference surface faces out so that if a ground glass is
put in alone, or is put in closest to the lens it is too
close causing a substantial focusing error. This can not be
corrected by any adjustments because the distance of lens to
ground glass no longer matchs the distance to the film.
  On cameras which were NOT designed for a built-in fresnel
it MUST be placed on the viewing side.
  One can check the coincidence of the ground glass surface
with the film surface on any camera witht a removable back.
It may even be possible to check by removing the lens board
but is more difficult that way. Measure the distance from a
reference surface (it doesn't matter what as long as it is
stable) using a depth micrometer. then insert a film holder
with a sheet of film in it. Measure again, the two
measurements should be identical. If there is a fresnel lens
in place in front of the ground glass the distance to it
should measure a little too short by approximately the
thickness of the fresnel. If it measures the same distance
as the film the ground glass surface will be too far away
and the camera is not designed for this set up.
  In theory the effective thickness of the fresnel will be
its physical thickness devided by the ratio of its index of
refraction to that of air (approximately 1.0). Since most
fresnel lenses are made of rather low index plastic the
physical distance is probably close enough, certainly close
enough to tell you if its in the wrong place.