PDF font doesn't display in Goodreader

Hi,

I’ve got a question about pdfs and Goodreader. A colleague sent me a pdf that was created in Windows version of Powerpoint. She installed a special font on her computer and used it in the Powerpoint file. She then saved the file as PDF and sent it to me. When I opened the PDF in adobe reader in OSX, I can see everything perfectly. But if I open it in Preview, the font does not display. Similarly, if I open the file in Goodreader on my ipad, that particular font does not display.

How can this be? I thought the point of using PDF was that fonts would always display properly no matter which computer was used?