The goal to facilitate a continuing medical education can be incorporated in the design of a clinical decision-support system. Developing a method for evaluating knowledge and skill development as part of evaluating the system is the aim for the research presented in this paper. The activity supported by the system was analyzed using Activity theory and structured into a protocol. Four clinicians were studied using the system for the first time, and their activity were assessed using the concept of Zone of Proximal Development. Initial results show how the system was used for clinician with different level of skills, and provide implications for further development of the methodology and the system.