Melbourne is 7 hours ahead of Riyadh
Best overlap: 8:00 AM to 11:00 AM in Riyadh is 3:00 PM to 6:00 PM in Melbourne.
The overlap falls at 8:00 AM to 11:00 AM in Riyadh, or 3:00 PM to 6:00 PM if you're in Melbourne. Roughly 3 hours of common time means scheduling is manageable; just avoid the very edges of the window. Just remember Melbourne changes its clocks for daylight saving and Riyadh doesn't, so confirm the overlap whenever the seasons turn.