In legacy PostScript printing workflows, F-series identifiers were sometimes used as substitution names when a printer did not have the requested font installed and swapped it for a built-in default.
CID is a font organization method; OpenType is a container format. Many CID-keyed fonts are delivered as OpenType files (.otf). You aren’t choosing one over the other.
What it is: Standard sans-serif. Free download: CID font F1 F2 F3 F4 F5 F6 F7 Fonts Free Download
First, let’s clear up a common misconception. F1, F2, F3, F4, F5, F6, and F7 are not actual font names like "Arial" or "Times New Roman." Instead, they are font registry aliases used internally by Adobe PostScript and PDF processors.
When a PDF is created and the original font cannot be embedded (or is deliberately omitted to save space), the system substitutes a "base font" and tags it with a simple label like /F1, /F2, etc. These are sometimes referred to as CID font synonyms or font dictionary keys. The Ultimate Guide to CID Fonts: Unlocking F1,
For example:
/F1 might point to Helvetica/F2 might point to Times-Roman/F3 could map to CourierIn the context of CID-keyed fonts (especially for CJK), a sequence like F1 through F7 often corresponds to standard Adobe-Japan1-6 collections or specific Type0 CIDFonts used in legacy systems like: Includes: Source Han Sans, Source Han Serif, Source
Important: The actual mapping varies depending on the software (Acrobat version, Distiller settings, or RIP). Therefore, downloading a file named "F1.otf" will rarely solve the problem. Instead, you need the actual font that the
/F1tag refers to.