Design the foundation as you would do for any foundation that has overturning. Enercalc or RISA footing are two programs I use. Just make it wide enough and long enough to resist the overturning, given an allowable soil value. Reinforce the sides and end for cantilever action. Make sure that you have stability. 1.5 times Dead load resisting moment has to be greater then the Overturning moment.
Frank