RadScheduleView have TooltipTemplate property which you can use to show custom tooltip on all appointments/occurrences.
The DataContext of the Tooltip however is not appointment but AppointmentItemProxy. This is custom class used for performance optimizations. It has Start, End, Subject and other appointment properties (but not all) which gives you the start/end of the current occurrence. It also has Appointment property which holds the master appointment. So in your scenario you have to create DataTemplate and bind the Textblock Text property to Appointment.Start and the next Textblock to Appointment.End.
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