Chat with tabular data

I have only tabular data consisting of number in pdf file. I want to summarise every tabular data in pdf separately with reference to each table. I want to use langchain to achieve this. I have already used RAG method. I tend to have different approach from RAG on my use case. Please suggest me some method to achieve this.

Moreover, do anyone know what evaluation metric can be used to evaluate the results that we have get from our LLMs. I do not have any reference text.