To embed a PDF onto your template you'll first want to access the template by going to Templates > My Templates > Click on the template > click customize to bring you to the template editor.

While in the editor navigate to the page/group that you wish to add the PDF.  You'll want to make sure you have a brand new element to add the PDF to.  If you do not have one this help article will show you how you can add a new element. 

Click in the empty cell within your template.  Click on the + to bring up the New Element Panel.

Choose PDF Viewer under Graphical Elements. 
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Choose your PDF you want to embed onto the template by clicking on the browse button.  You'll then be able to choose any PDF from your files.
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Once your file is selected click on the Create button. 
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Your PDF will now be embedded onto the template. 

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