Which BookFormatType for PDF?

I use the BookFormatType for Google’s Book feature.

My structure is okay so far according to the SDTT.

I offer:

• Paperback
• EBook

But what should I use for a PDF? Or should I use a different Rich Snippet for the PDF?

PDFs are e-books

If the PDF contains a book, it is an e-book. (cf. Wikipedia: E-book: Formats and Comparison of e-book formats: Portable Document Format).

So for such a PDF, provide a Book with bookFormat = https://schema.org/EBook.

If you want to provide the file type of the e-book, you can use the fileFormat property with a value of application/pdf (IANA Media Types).

A book in multiple formats

As you offer different formats of a book (paperback, multiple e-books etc.), you should use one Book item that represents the work, and another Book item for each format.

You can link them with the workExample property:

Example/instance/realization/derivation of the concept of this creative work. eg. The paperback edition, first edition, or eBook.

JSON-LD example

{
  "@context": "http://schema.org/",
  "@type": "Book",
  "name": "Gone with the Wind",
  "author": {
    "@type": "Person",
    "name": "Margaret Mitchell"
  },
  "workExample": [
    {
      "@type": "Book",
      "name": "Paperback of 'Gone with the Wind'",
      "bookFormat": "https://schema.org/Paperback"
    },
    {
      "@type": "Book",
      "name": "PDF of 'Gone with the Wind'",
      "bookFormat": "https://schema.org/EBook",
      "fileFormat": "application/pdf"
    },
    {
      "@type": "Book",
      "name": "EPUB of 'Gone with the Wind'",
      "bookFormat": "https://schema.org/EBook",
      "fileFormat": "application/epub+zip"
    }
  ]
}