Do site da Adobe :
When a font cannot be embedded because of the font vendor’s settings, and someone who opens or prints a PDF does not have access to the original font, a Multiple Master typeface is temporarily substituted: AdobeSerifMM for a missing serif font, and AdobeSansMM for a missing sans serif font.
Se você quiser ter certeza de que o documento parece e imprime conforme o esperado, incorpore as fontes usadas ao criá-lo.