It is often helpful to see examples of others’ writing to help you think about your own. Here’s a sample research prospectus (below) from one of my former students. This is for example purposes only. The student did a number of things well, but there were also several areas that could have been improved. Nevertheless, this sample contains many of the sections that you should include in your own prospectus.
One important thing that is not in this sample that should be in yours, is a bibliography with sources divided into primary and secondary sources with annotations for the secondary sources.