The one piece windscreen changes between models. This shows the measurements from a 1930 RK, which seems to directly mirror what is found on a 1929 RF (3) model with similar separate roof peak, although there is variation from 16.5 to 16.75″ at the outer edge. The tapering under-section is also the same, although some cars seem to have a regular 1 3/4″ throughout.
Theses are the dimensions (in white boxes) of an earlier RF (2) with integral windscreen peak and the under-section is seen to not be tapering; please make contact if you have different.
One 1930 AE Tourer has height at outer screen of 17.3″ approx, same width as others, but note this is a two piece screen so not directly comparable.
If they differ from those stated above, could you add your own dimensions by way of a comment on this post, or by making contact directly.