What does a research proposal for PhD applications consist of?
Propose a research topic, maybe using a hypothesis (it depends on you subject area): clearly identify what you want to find out.
Show why this a relevant piece of research for the rest of us.
Explain how you would attack the topic, what is your intended approach.
Show related research where others, if possible well known researchers, have done their research.


During your research, all these elements could change, however, if you lack of an idea before, it will be hard.