It'll work - there aren't minimum requirements.
But I'd need to know a little more about your use case to know if it's a sensible idea.
For example, how long are your documents? The smallest production cluster that R&R provides is 32GB, so you'll be paying the monthly fee for that even if you only put 4 tiny documents in. That may not be a very cost-effective way to solve your particular problem.
What do you want it to return in response to queries? If it's the whole document that you want it to return, then every query could end up returning the same 4 documents, just in a different order each time... which doesn't sound like a very helpful thing to do.