Rule to tag based on attachments w/PDF's only

I tried setting it as header:
Content-Type: application/pdf

But it doesn’t work, maybe because that appears in the message body source and not the header?

I’m trying to create a tag for any mail that contains a PDF file.

From what I have read Content-Type: is correct as it does appear in the header for an email w/attachment that I tested with. The attachment was a PDF but this was what was in the header of the test email:

Content-Type: multipart/mixed; boundary="------=_MBFC478E13-09FF-42CC-BCD0-AC046F0645C9"

That won’t work because Content-Type: application/pdf is not in the message header.

The best you could do is probably: