How to serve out-of-page ads in Google Ad Manager

Export your tag and be sure to choose DFP from the Adserver dropdown.  

Add a new creative to your Order in DFP, by selecting "Custom".   Paste the Adventive tag into the Standard HTML code block.   Select "Out-of-Page" from the Targeted Ad Size dropdown.  This will activate additional macro options.   Place your cursor directly after the "oop=" parameter in the Adventive Tag.   Click "INSERT ESCAPED VIEW URL MACRO"  This will result in the OOP macro being inserted (%%VIEW_URL_ESC%%).     Proceed with configuring the remaining creative options according to your site requirements.