diff --git a/DOC.md b/DOC.md
index e21f67c..375f76b 100644
--- a/DOC.md
+++ b/DOC.md
@@ -181,17 +181,19 @@ OPTIONAL.
 ##### OIDC_IDTOKEN_SUB_GENERATOR
 OPTIONAL. Subject Identifier. A locally unique and never reassigned identifier within the Issuer for the End-User, which is intended to be consumed by the Client.
 
-Is just a function that receives a `user` object. Returns a unique string for the given user.
+Is just a function that receives a `user` object. Returns a unique `string` for the given user.
 
 Default is:
 ```python
 def default_sub_generator(user):
 
-    return user.id
+    return str(user.id)
 ```
 
 ##### OIDC_RSA_KEY_FOLDER
-REQUIRED. Path of the folder where `OIDC_RSA_KEY.pem` lives. This RSA key can be easily created using `python manage.py creatersakey` command.
+REQUIRED. Path of the folder where `OIDC_RSA_KEY.pem` lives. Used to sign/encrypt `id_token`. The package will automatically generate a public key and expose it in the `jwks_uri` endpoint.
+
+You can easily create it using `python manage.py creatersakey` command.
 
 ##### OIDC_SKIP_CONSENT_ENABLE
 OPTIONAL. If enabled, the Server will save the user consent given to a specific client, so that user won't be prompted for the same authorization multiple times.