If you know the person who generated the document, the cleanest fix is to ask them to export the file again with proper settings. Tell them to enable or "Subset Fonts" in their PDF export settings. This locks the required font data directly inside the file so it displays identically on every computer in the world.

Some users have found success by opening the problematic PDF in macOS Preview and using Export as PDF . This can sometimes "bake in" the font data so it is readable in other programs.

Open the problematic PDF file in or a similar viewer.

CID (Character Identifier) fonts are a type of PostScript font format designed to handle languages with massive character sets. Standard Western fonts usually contain a few hundred characters. In contrast, East Asian languages like Chinese, Japanese, and Korean (CJK) require tens of thousands of unique glyphs.

Ghostscript is an open-source interpreter for PostScript and PDF. The ghostscript-fonts-std and specialized CJK packages often contain CID-compatible fonts that can map F1-F4. Where to find: Ghostscript GitHub or SourceForge pages.

"F1" through "F4" are generic placeholders generated by the PDF exporter to represent different weights or styles (e.g., F1 might be Arial Bold Arial Regular CID Encoding:

If you need specific help resolving a PDF printing issue, please tell me: What application are you printing from? What is the exact error message? What operating system (Windows/Mac/Linux) are you using?

2. Install the Official Google Noto Fonts (Free & Open Source)

Unlike traditional fonts that use a simple one-byte character map (meaning they can only handle 256 characters), CID fonts use a multi-byte character mapping system. This allows them to support tens of thousands of characters—essential for Korean Hangul, Japanese Kanji, and Chinese Hanzi.

Search for the official on Adobe's website.

"F1" is not the font's name. It is a handle . The PDF reader looks up "F1" in the document's resource dictionary to find the actual font name (e.g., AdobeHeitiStd-Regular ).