Consumption: Consumption indicates how many BP are required to keep the kingdom functioning each month. Your kingdom’s Consumption is equal to its Size, modified by settlements and terrain improvements (such as Farms and Fisheries). Consumption can never go below 0.
The old Kingmaker rules had consumption equal kingdom size plus districts minus (the effect of) farms. The above quoted rule just says "modified by settlements". Is this meant to be just number of settlements, regardless of their size, or should we still be using the number of districts?
My understanding is that each settlement district increased Consumption by 1, as I didn't see anything to the contrary.
Basically assume that if rules from Kingmaker were not explicitly changed by Ultimate Campaign, keep them.