Helm charts in Rancher 2.1

I would like to install chart on rancher 2.1. i have tryed to install the helm chart directly over the rancher but it dosent work

docker exec -i -t serene_sammet /bin/bash
helm install stable/nfs-client-provisioner --set nfs.server=x.x.x.x --set nfs.path=/exported/path
triller not found

how can i use helm on rancher 2.1?