diff --git a/README.md b/README.md
index b60bebe..ed23927 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,11 @@ Pass configuration with `env` vars
 
 1. `SSH_PRIVATE_KEY` [required]
 
-This should be the private key part of an ssh key pair. The public key part should be added to the authorized_keys file on the server that receives the deployment.
+This should be the private key part of an ssh key pair. 
+The public key part should be added to the authorized_keys file on the server that receives the deployment.
+
+The keys should be generated using the PEM format. You can us this command
+`ssh-keygen -m PEM -t rsa -b 4096`
 
 2. `REMOTE_HOST` [required]