The RPCAP documentation is not very extensive at present, but ought to be enough to get going with. The documentation included with the package comprises of a README file , an INSTALL file on rpcap build and installation, and an example program , all of which are included in the distribution archive. Using the rpcap system is quite easy, if you've had some experience with libpcap based capture software. The client_test program included with the rpcap distribution is a heavily commented illustration of rpcap application, and ought to serve as a good guide to programming with rpcap.
SInce the RPCAP API is a subset of the libpcap API, with function call signatures that match libpcap exactly, libpcap programming examples too apply to RPCAP. However, do remember that some of the libpcap functions are not implemented in RPCAP, so please check the RPCAP documentation.