Watching local iTunes content requires the Home Sharing option be enabled in iTunes (on the host computer) and you must enable Home Sharing on the device (previously ONLY and AppleTV or a Mac)... I would think that the same requirement would be in place, and not sure if/how one can log into/enable Home Sharing via Roku (or the TV+ app on Roku). I'm guessing the answer to your question will be "no".
The Apple TV app for Roku currently supports neither Homesharing nor Airplay, so there is currently no way to stream content from an iTunes server. However, given that your files are not DRM protected, there are other ways to locally stream them such as the Roku Media Player or Plex, but it will require setting up software on the computer (Plex server or DLNA server).