Product knowledge plays an important role in identifying the requirements of the desired variant and configuring the existing product to the present needs of a customer. The success of a product-based business depends to a great extent on how efficiently and accurately the existing product knowledge is utilized for customization needs. Oftentimes however, product knowledge resides with few key individuals in an organization. In the absence of their involvement, project teams may redevelop product features unnecessarily, resulting in an effort overhead. Such overdependence poses a risk to projects. To identify the requirements for the variants accurately and efficiently, we need to have a thorough knowledge of the existing product features. In this paper, we discuss our work on representing product knowledge and reusing it in a Requirements Engineering (RE) exercise for a large project involving product customization. We present our experience from using the configurator for requirements gap analysis and customizations.