Network slicing has been the key technology to support diverse applications in the fifth-generation (5G) wireless communication networks, via tailoring the common physical network infrastructure to a number of logical sub-networks (slices). The tenants can lease slices to provide customized services, increasing the network flexibility. In this paper, we introduce the spatial dimension (i.e., beams) to the radio access network (RAN) slicing, where beam-level is finer granularity than cell-level in RAN slicing. Specifically, we analyze and formulate a beam based tenant profit model. Then, we further propose a tenant beam management method of the RAN slice based on the model. The simulation and numerical results verify the effectiveness of our proposed method to improve tenant profits.