Your receiver should show up under airplay speakers as long as it is connected to your network in some way. If not you will have to connect it via ethernet or via wireless if your Denon receiver supports it. Once connected should be good to go. Here are some more steps on using airplay from your apple devices.
This site contains user submitted content, comments and opinions and is for informational purposes only.
Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site.