Your choice of film is a good one...it expands in contrast nicely. You do want more than "normal" contrast. How much more development will depend on the amount of contrast already available in the scene. I prefer to make negatives that require no contrast agent when making pt/pd prints, so my negs tend to have lots of contrast.

D-19 will probably be over-kill if the scene already has a range of 5 or more stops in it. Developing in D-76 for 50% longer than "normal" might get you the neg you want. I am a trial and error sort of guy, so I would take two negs of a scene and process one at 50% longer, then see what it looks like to determine how to develop the second one.

Personally, I use UK's Terry King's suggestion of using Ilford PQ Universal Developer for FP4+. Does a very nice job for pt/pd. I use all sorts of dilutions/time combinations depending on the contrast in the scene and the target process for the image (more contrast needed/wanted for carbon than pt/pd). For pt/pd, an average scene might get the PD developer mixed 1:16 for 6 to 8 minutes at 20C, for example.

But what I like about pt/pd (and even more so with Carbon Printing) is the process's ability to reproduce the light values in scenes of very high contrast. So I tend to look for light that otherwise I would probably not use if I was making silver gelatin prints. Things like sunlight coming through the deep forest, etc.

For the below image (in carbon) I actually used the time for "normal" development as I measured 13 stops with the Pentax Digital Spot Meter. ..might have been a greater range as the meter read 0 up on the cave's roof (who knows how much below 0 it was) and the sunlight on the sand read 13. Sorry about the dusty print scan...

Vaughn