NNB-958H RAM options

Hi all, I want to increase the RAM in my NNB-958H (Serial number 7310234-001). The current single stick in there is a Samsung M471B5173BH0-CH9 - which I note is 1xR8, that is single ranked. I’m guessing theres a fair amount of compatibility but I’m not sure it will work with dual ranked RAM, which is commonly available. I can’t find any single ranked now, it’s all 2xR8. If anyone has this laptop or could indicate compatible RAM that would be great. It’s moving a bit slowly with a single 4Gb stick but would be much better with 2x4Gb or 2x8Gb if that were possible.