Since Cid+F1 is a mask, your job is to reveal the true font face. Here is how you do it across different software:
The PDF might have been saved without embedding the font subset. Use Adobe Acrobat Pro > Print Production > Flattener Preview to convert text to outlines (shapes). This is a nuclear option but eliminates font dependency. Cid Font F1 F2 F3 Download -
This usually happens when sending a job to a professional printer (Imagesetter). Since Cid+F1 is a mask, your job is
Solutions:
You open a client-supplied AI or EPS file. A pop-up says: "The font Cid+F1 is missing. Affected text will be displayed using a substitute font." Since Cid+F1 is a mask