Many of the WordPress Download Manager Pro users ask us how they can preview PDF files for site visitors, as well as provide an option to download the file. Since the visitor wants to know what is inside the PDF file before downloading it or simply wants to read it online.
Here's the add-in WordPress PDF Viewer . You can easily configure the PDF preview with this Download Manager add-on.
The default document viewer with WordPress Download Manager Pro uses Google doc viewer that only works for public (accessible to all visitors, this is a WPDM access configuration) PDF documents. But you can use WordPress PDF Viewer add-on to show protected documents / members only.
So, how does the PDF embed on your site? Simply follow these 4 simple steps:
1) Create a Download Manager package and attach your PDF file there.
2) Create a link / page template with  template tag. Or you can use the existing document preview page template (single column with document preview).
3) Set this template as a link / page template in the package configuration. Now the package details page will show the preview of the attached PDF file.
4) Use the custom link template with the template label [doc_preview] when using the package's short code to display the PDF elsewhere.
The publication How to insert PDF files into WordPress first appeared in the WordPress Download Manager.