There is no option offered by RealPlayer to combine videos together. If you'd like to join several files together to create a seamless video, then Joyoshare video joiner can perfectly meet your requirements. It's able to combine files, no matter the format is the same or different, at a fast speed to 60X. Also, the output quality of your new complete video is lossless. It's handy to cut out needless sections too.
If you want to check more tools, this multimedia software is suitable.