The budget shall reflect as nearly as possible the estimated revenues and expenditures for the year for which it is prepared. The commissioners shall, upon adopting the budget, adopt the appropriation measures required to put it into effect, and shall fix such rate of taxation upon the valuation of the property taxable for county purposes as will, together with all other estimated revenues of the county, excluding operating, capital and other reserve funds, raise a sufficient sum to meet the said expenditures.
16 P.S. § 1783