How do you attach a PDF to an email in PDF form?

Drag the PDF in question directly into the Body of the e-mail. Depending on the size of the e-mail and PDF - if using iCloud Mail Account and it exceeds the 20 MB size, Mail might offer a message stating this can not be done.

Millerbd53 wrote:

How do you attach a PDF to an email in PDF form, using Mac Mail?

Use the attachment icon:

If you still have an issue, try compressing it first; Control click on the PDF>Compress then attach the .zip file

or

Compress a PDF in Preview on Mac - Apple Support

Just like any other attachment. Either use the paperclip icon or drag the PDF file to the email.

Run a test and send yourself an email and attach the pdf an see how it looks

No, it may show the "preview" of the PDF, but it's still a PDF.

Mail, will show the entire PDF in the email if it's a one page PDF, but it's still in PDF format.