Hi, Jos,
I'm sure different people will jump on this question with more answers than this....
I believe the book "MegaFox: 1002 Things You Wanted to Know About Extending VFP" has a section on utilizing PDFs and extracting data from PDFs. The book is available on Hentzenwerke's site.
I also think Rick Schummer has done presentations on this at different conferences on this topic as well.
Kevin