Megaphone supports using Podtrac measurement. You can read the Megaphone help article here:
http://support.megaphone.fm/en/articles/2792555-podtrac-tracking.
Here are the steps to follow:
Login to Megaphone
Navigate to your podcast through the Podcasts tab
Click into your show
Select the gear icon in the top right corner
On the pop up screen, click the "Megaphone Settings" tab
Check the box next to "Enable Podtrac"
Click Save