The fonts identified as CIDFont F1 through F7 (or simply F1–F7) are not specific brand-name fonts you can download from a website. Instead, they are generic internal aliases created by PDF creation software when fonts are embedded or encoded using a "Character Identifier" (CID) system.  Why You Can't "Download" Them 

mutool show yourfile.pdf | grep -i "f4"

Here are a few reliable sources to download CID fonts F1, F2, F3, F4, F5, F6, and F7 for free:

). Look for the list of fonts. If you see "CIDFont+F1," check if there is an "Actual Font" or "Substitute Font" listed next to it. Common Substitutes