You can handle the RadScheduler ActiveViewChanged event and check if the new view type equals to SchedulerViewType.Month. If the new type equals to SchedulerViewType.Month then you can change the DateFormat property of the RadSchedulerNavigator to something like "MMMM yyyy".
The code inside ActiveViewChanged event will be something like:
(e.NewType.ViewType == SchedulerViewType.Month)
"dd MMMM yyyy"
I know the code I provided doesn't match exactly Outlook look, but since RadScheduler can scroll months and have half a month (lets say Half January and Half February) in view at the same time, this is the easiest and practical solution that comes to my mind right now.
Please, let me know if this solution works for you.