A litre is a cubic decametre, or a tenth of a metre cubed.
So a cube of side 10cm has a volume of one litre.
A cube of side 30.8cm has a volume of one cubic foot.
So the number of litres in a cubic foot is (30.48x30.48x30.48) divided by (10x10x10). Or 28316.846592 / 1000, which is 28.316846592 litres per cubic foot.
In SI any unit prefixed with kilo is multiplied by 1000 so a kilolitre is a thousand litres.
So there are 28.316846592 / 1000 or 0.028316846592 kilolitres per cubic foot.