I am using llama2 model to create a RAG based LLM with huggingface sentence-transformers/all-MiniLM-L6-v2 embedding and pinecone to store information as Vector database. I am feeding a pdf and am able to get results using similarity search on query from vectors in pinecone. I am facing issue in providing the best-k results as context in RetrievalQA function, specifically its retrieval argument: