How do I insert page numbers into a PDF? (I do not have the option to select header/footer in the tools menu)

I had to fiddle with this too. It used to be so much easier to find the "Page Numbering" dialog box in the older versions of Acrobat. Now it is somewhat hidden (it seems in favor of Bates Numbering, which I'm assuming you are not looking to use). I was finally able to figure it out! Here's what to do:

1.) Start by opening your PDF (in Acrobat Pro DC)

2.) Go to "Organize Pages"

3.) Select the pages that you wish to renumber (choose more than one at a time by holding down the SHIFT key)

4.) With the pages selected that you want renumbered, either...

     • Right-Click the mouse on a PC

       or

     • Control-Click the selected pages on a MAC

5.) A contextual menu will appear, where you'll choose "Page Labels"

6.) This opens the "Page Numbering" Dialog Box, where you can renumber your pages from.

Best of luck!

-Joanne Watson

You can add page numbers with Acrobat DC -- here are the instructions: Acrobat Help | Add headers, footers, and Bates numbering to PDFs

The trick is to open your document, click on Tools, then select the Edit PDF tool. Then you should see this.  Select Header & Footer to open the dialog where you can add the page numbers.