In a PDF document, these labels indicate that the original font information is missing or renamed for internal technical reasons:
Avoid shady font websites promising a direct "f1.ttf" download—those are almost always scams or malware. By using the methods outlined above, you will resolve the dreaded "Missing CID Font" error without compromising your system’s security. cid font f1 f2 f3 f4 free download free
If you have downloaded a font and it isn't working, check these common issues: Understanding Font Types and Uses
If a user manages to extract a CID font from a PDF (using forensic software), they must be aware of copyright. CID Fonts : These are type of PostScript
If you are seeing these names in a PDF or an editor, try these workarounds to make the text readable or editable: Impossible fonts to be found / Fontes impossíveis de achar
or "anonymized" names created by software (like InDesign or Word) when a PDF is exported.
Since you cannot download "CID Font F1," you should look for legitimate free fonts on reputable sites: CID+ Fonts - Adobe Community