  Scaling limits of the SOS and RSOS models in the regime~III are considered.
These scaling limits are believed to be described by the sine-Gordon model and
the restricted sine-Gordon models (or perturbed minimal conformal models)
respectively. We study two different scaling limits and establish the
correspondence of the scaling local height operators to exponential or primary
fields in quantum field theory. An integral representation for form factors is
obtained in this way. In the case of the sine-Gordon model this reproduces
Lukyanov's well known representation. The relation between vacuum expectation
values of local operators in the sine-Gordon model and perturbed minimal models
is also discussed.
