Can I add more nodes to a currently running RKE cluster using Rancher?


I created a RKE cluster on Amazon, using 3 nodes (with both roles, master and slave). I was surprised on how easy was to deploy a cluster using Rancher, it was a matter of seconds. However, I am unable to modify from Rancher a RKE cluster already created on AWS. If after creating the RKE cluster, I decide to add more nodes, is there any way to do it ? I see an option to modifify the cluster, but when I tryed to modify the cluste and increase the number of servers on the pool to 4, and save it, I got an error.

Thks !