There are two methods:

    - including "absolute" PostScript.  PostScript that knows where
      it goes on the page, and decides its own scaling.
      All versions of ditroff support this one way or another.
      CAT troff does as well when coupled with psroff.  This is
      most often supported by some permutation of \! or \X'...'
      directives.

    - including PostScript, automatically scaling and placing the
      image.  This requires that the PostScript be EPS (so that the
      size and origin of the image is accessible).  Groff and
      DWB 3.3 have facilities for including EPS files and automatically
      placing/scaling them on the page, including leaving space in the
      troff text for the image.  See if your documentation includes
      remarks about "PSPIC", "PS" or other similar macros.

      Psfig (comp.sources.unix archives) is a troff preprocessor which
      will permit this sort of automatic placement/scaling with an
      older version of ditroff (such as DWB 2.1) as long as the backend
      printer driver understands it.  Psroff 3.0 and Adobe Transcript
      support psfig with ditroff, but only Psroff 3.0 will support
      psfig with CAT troff.

Caution: many PC and MAC graphics packages generate sloppy PostScript which
cannot be gracefully included in other documents.