Dart & Kraft Inc. of Northbrook, Ill., reported third-quarter earnings that were adversely affected by various one-time charges, some of which have been previously disclosed in connection with the impending spin-off of certain businesses. Both earnings per share and net income were down sharply. Per-share results and net income in the 1986 third quarter include after-tax charges of approximately $81 million for business and facility rationalizations as well as costs associated with the spinoff of the company's direct-selling, food-equipment and certain consumer businesses. Dart & Kraft third-quarter earnings from continuing operations, which now consist of Kraft Food and Duracell battery businesses, also were down, compared to last year. Earnings from continuing operations were affected by a higher-than-anticipated tax rate, due to the absence of investment tax credit for the period and foreign currency losses that were 3 cents per share in the quarter versus none last year. John M. Richman, chairman and chief executive, said the actions reflected by these charges, while substantially reducing third-quarter earnings, are certain to enhance the profit potential to both Dart & Kraft's continuing businesses. Commenting on continuing operations, Richman said, Kraft, representing over 90% of sales and profit, posted higher profit in all of its business groups except dairy, which had a significant shortfall. Duracell profit was unchanged.