Because "F1" through "F4" are just temporary internal labels generated uniquely for that specific PDF, Why You Can’t Find a "Free Download"

If you are the person who generated the PDF and your clients are complaining about missing F1/F2 CID fonts, you must alter your export settings:

If you are a graphic designer, archivist, or administrative professional creating PDFs and your clients are complaining about "CID Font F1" errors, you can fix this at the source using your design software:

Press Ctrl + D (Windows) or Cmd + D (macOS) to open the Document Properties . Step 3: Click on the Fonts tab.