I've never been able to do that in TOS. You can do it in stockcharts.com using a colon, for instance to divide the HUI by the price of gold enter: $HUI:$GOLD Only problem is if you're not a member you're restricted to 3 years of data and only 2 timeframes.
What exactly are you trying to do? I think I know the problem. You need to use prophet charts on TOS to do ratio charts. Not the regular charts.
Anyone know how to chart ratios of futures in prophet? I've been using it for equities and indices but anytime I've tried to do it with futures it gives an error message saying the ratio is not valid.