you are not assigning anything to Num except 0. I am pretty sure it ought to be assigned the value of Size at some point, or else it can be merged with Size. It almost looks like Size and Num ought to be the same thing. Be advised that in your comments you refer to Size$ which would be a string variable, but in you program, Size is a numeric variable, a SINGLE.
Also, you are not assigning anything to Hours. I don't see any mention of hours in the specification.
Also, you have:
LET RevenueSubtot = RevenueSubtot = Revenue
I'm pretty sure that should be:
RevenueSubtot = RevenueSubtot + Revenue
Except that you are not assigning anything to Revenue either. Perhaps Revenue is the same as AmountOwed, the same way Size is the same as Num, presumably?
Also, you have both NamSav$ and NamSave$, but you don't use the values that you assign to them...