Adding a PDF file to your app layout is easy. Instead of dragging a "Blank page" object to the grid you will simply drag the "PDF block", found on the right-hand column.
When you have your new PDF block selected a panel will be visible in the upper right-hand corner and you will see two fields "Name" and "Tag". This is where you can name and tag your PDF.
Click inside the "File" box underneath the "Name" and "Tag" fields and locate the PDF file you want to place in your page.
You can also link to the PDF page from any of the other pages using "Page links".