If you are trying to open a PDF and getting an error like "CID Font F1 not found," do not try to download the font. Instead:

CID (Character ID) fonts are a font format developed by Adobe to support large character sets, especially for CJK (Chinese, Japanese, Korean) and other languages requiring many glyphs. CID-keyed fonts separate character collection (CID) from glyph outlines and can be packaged in several font file types (Type 1/CFF, OpenType/CFF, TrueType-based). The terms "F1, F2, F3, … F7" are not standardized CID font family names; they commonly appear as internal or exported font names in PDFs, font subsets, or generated font files (for example when PDF authors or font-embedding tools rename fonts to short labels like F1). Those labels by themselves are ambiguous — they usually indicate a font resource index, not a published family.

Better alternative: Noto Sans CJK TC or Source Han Serif

If you are a sysadmin or power user, create a self-contained Better_CID_Fonts folder.

Using the free fonttools Python library:

# Download all Noto CJK fonts
wget https://github.com/googlefonts/noto-cjk/raw/main/Sans/OTF/Japanese/NotoSansCJKjp-Regular.otf
wget https://github.com/googlefonts/noto-cjk/raw/main/Serif/OTF/Japanese/NotoSerifCJKjp-Regular.otf
wget https://github.com/googlefonts/noto-cjk/raw/main/Sans/OTF/SimplifiedChinese/NotoSansCJKsc-Regular.otf
# ... repeat for TC, HK, Korean.
If you clarify whether you need a download link, a technical spec, or help with a PDF font error, I can give you an exact answer.
These fonts are widely popular among developers and terminal users because they are clean, highly legible, and optimized for coding.
Here is the guide to the Write font family (F1–F7), what makes them "better," and where to find the free download.