Files with phf extension are used for FontLab Photofont. They contain Photofont fonts.
PHF file extension - Photofont font
What is phf file? How to open phf files?
File type specification:
The phf file extension is associated with FontLab Photofont and used for font files.
Photofonts are photos that looks like a regular font. User can apply typeset several lines of text using a custom font they choose.
This phf file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.