Within the limitations and restrictions as further provided in this Article, the total area of all signs which an establishment is permitted to display shall be computed according to the following formula:
One (1) square foot of sign area per one (1) foot of street frontage or two (2) square feet of sign for each lineal foot of the front width of the business.
provided, however, that no establishment in any district shall display more than three hundred (300) square feet of sign on any street front.