A technique of synthesis of nearly complete two- and three-component systems is described, which consists of one-cathode, multiple-target, rf co-sputtering of the constituent elements onto one large substrate. A new and simple approximate method of compositional determination of co-sputtered films is introduced which is based on the assumptions of superposition of the sputtered species and the constancy of geometry-dependent deposition profiles. Compositional analysis of any portion of the deposited film can be obtained from film thickness measurements and the knowledge of the deposition profiles, which need to be determined only once for a given sputtering geometry.