This paper presents a clock synchronization skeleton based on RTAI (Real Time Application Interface). The skeleton is a thin layer that provides unified but extendible interfaces to the underlying operating system, the synchronization algorithms and the upper level applications in need of clock synchronization. The skeleton provides synchronization support to a system, whereby the achieved accuracy is the best obtainable given this software structure. By connecting an algorithm and a communication module with the skeleton, a system becomes capable to run with synchronization support. To demonstrate and validate the design, the skeleton has been tested successfully with two different synchronization algorithms based on the CAN bus. Other algorithms and communication technologies can also work with the skeleton, as long as they provide the necessary functionalities for clock synchronization