A major drawback of OFDM is its large peak to average power ratio (PAPR). While subcarrier reservation is a common approach to combat this problem, little is known about the performance of algorithms that utilize subcarrier reservation. By combining properties of sparse signals with an abstract form of the Uncertainty Principle related to multiple subcarrier signals, we design an efficient iterative method for constructing OFDM signals with lower PAPR. Unlike most existing subcarrier reservation methods, our method provides a guaranteed upper bound for PAPR reduction as well as guaranteed rates of convergence. We also explore the limitations of the method of reserved subcarriers that are imposed by the restricted isometry property (RIP). Numerical simulations demonstrate the performance of the proposed method, and we compare the performance of our method with reserved subcarriers obtained via convex optimization.