If you have access to the source document (or if you can open it on a PC), try printing the PDF to a new PDF file. This "flattens" the document.
to convert the text to outlines. This removes the need for the font entirely. Official Alternatives cidfont f1 font free download for mac
Reasons to avoid:
However, is not a single, downloadable font file like "Arial" or "Helvetica." It is a placeholder label used by PDF generators to describe an embedded CID-keyed font . This error usually means the font was not properly embedded when the PDF was created, and your Mac doesn't know which actual font it refers to. The "CIDFont F1" Fix: Why You Can't Simply Download It If you have access to the source document