Correct torque amount for carbon railed seat?

Hi, I have a Toupe with carbon rails, and it's on my Cobble Gobbler seat post (2018 Roubaix). The bike came with another heavier and less comfortable seat, so I swapped it. However, I only had a torque wrench (Ritchey) that goes to 5Nm. Doesn't seem to be enough, as the seat rotates and I have...