Yes, you can traffic Spoutable through Ad Manager or another ad server. 

It is best to set up non-IAB sized Spoutable placements as an out of page (1x1) placement, and to serve in a friendly frame (not a "Safe Frame").

To access your Spoutable creative code: 

• Click the Manage tab
• Click Get Embed Code
• Click Show DFP creative code

Related Articles: 
How do I add the Spoutable code to my site?
I added the code, why can’t I see Spoutable on my site?