Here’s a list of some useful Web sites for learning more about PDFs and PDFpen:
Smile’s PDFpen Support and FAQ page: You can find answers to common questions and instructions on how to contact Smile for individual support questions.
PDFtools.com’s PDF Primer: This white paper offers a good summary of the technological underpinnings of the PDF standard and the reasons that PDF was developed.
Planet PDF: This site, run by Nitro PDF software, contains a number of useful technical articles about PDF, and hosts a forum of PDF users and developers.
Prepressure.com: Customer support engineer ...