I suspect
swchris wants to display the PDF within the DokuWiki page (embed).
If that's the case, sorry
swchris, that's not possible.
You can display images of the PDF, or, depending on the type of PDF - extract the content and display that. But first you'd have to process the PDF (extract the data if it contains data and massage it so that it can be converted into DokuWiki code, or take pictures of it and embed those images in the DokuWiki page). The
docpdf2dokuwiki plugin
might help -
in some circumstances.
Notes - I haven't used that plugin; PDFs can be either simply images - or contain images, text, forms, and markup/formatting, they can even be encrypted to make it difficult for you to extract content. tl;dr? Your mileage will vary when extracting information from PDFs.
tl;dr? If you upload a PDF to DokuWiki you can only display a link to it in a DokuWiki page. Clicking on that link can allow it to be displayed in your browser or your locally installed PDF browser.