Rule-based and object-oriented techniques are rapidly making their way into the infrastructure for representing and reasoning about semantic information on the Web. Combining these two paradigms has been an important objective and F-logic is a widely adopted formalism that achieves this goal. However, the original F-logic was lacking the notion of instance methods --- one of the most common object-oriented modeling tools. Extending F-logic with instance methods poses new, nontrivial problems. It requires a different kind of nonmonotonic inheritance and impacts much of the semantics of the logic. In this paper we incorporate instance methods into F-logic and develop a complete model theory as well as a computation framework for the extended language.