The continued growth in enterprise social networks is fueled by the need to enable productivity and innovation. Reducing the constraints to communication and knowledge sharing of a globally distributed workforce, will facilitate the workflow. People finder systems are one of the main solutions in enterprise social networks which are reducing these constraints leading to time and cost savings. Finding expertise efficiently helps organizations to unlock knowledge within the enterprise, solve problems, and identify collaborators. However, the following challenges still exist: validating expertise, determining responsiveness and accessibility, and managing expert profiles. In this paper, we propose the fuzzy OWA technique as a novel approach to ranking candidates in expertise search. We consider its application in open innovation intermediaries where the search for partners and expertise is at the center of the business model. In addition, we demonstrate its application in a software tool (InsERT) as part of a larger enterprise social network implementation.