Create prompt with placeholders using context from RAG

I’m not able to create a prompt template with a placeholder for context, i.e retrieval information from RAG:

In ‘LangChain Chat with Your Data’ → ‘Question Answering’ → ‘Prompt’:
It seems that template has placeholder {context} for retrieval information from RAG:

I want to use it but add some more placeholders to my template like ‘LangChain for LLM Application Development’ - > ‘Models, Prompts and Output Parsers’ → ‘Prompt template’:

When i try to do this i get 'KeyError: ‘context’ which means that i don’t add ‘context’ to .format_messages. but context should get internally from RAG.

Any help?