Specify usage of registrationId parameter

Specify that the registrationId parameter must be used when the device is enrolled using a custom registrationId

Author: fgheysels

articles/iot-edge/how-to-provision-devices-at-scale-linux-on-windows-tpm.md

@@ -139,6 +139,12 @@ Simulated TPM samples:
    ```powershell
    Provision-EflowVM -provisioningType "DpsTpm" -scopeId "SCOPE_ID_HERE"
    ```
+   
+   If you have enrolled the device using a custom **Registration Id**, you must specify that Registration Id as well when provisioning:
+   
+   ```powershell
+   Provision-EflowVM -provisioningType "DpsTpm" -scopeId "SCOPE_ID_HERE" -registrationId "REGISTRATION_ID_HERE"
+   ```
 
 # [Windows Admin Center](#tab/windowsadmincenter)
 
@@ -167,6 +173,12 @@ Simulated TPM samples:
    ```powershell
    Provision-EflowVM -provisioningType "DpsTpm" -scopeId "SCOPE_ID_HERE"
    ```
+   
+   If you have enrolled the device using a custom **Registration Id**, you must specify that Registration Id as well when provisioning:
+   
+   ```powershell
+   Provision-EflowVM -provisioningType "DpsTpm" -scopeId "SCOPE_ID_HERE" -registrationId "REGISTRATION_ID_HERE"
+   ```
 
 :::moniker-end
 
@@ -272,4 +284,4 @@ Use the following commands on your device to verify that the IoT Edge installed
 
 The device provisioning service enrollment process lets you set the device ID and device twin tags at the same time as you provision the new device. You can use those values to target individual devices or groups of devices by using automatic device management.
 
-Learn how to [deploy and monitor IoT Edge modules at scale by using the Azure portal](how-to-deploy-at-scale.md) or [the Azure CLI](how-to-deploy-cli-at-scale.md).
+Learn how to [deploy and monitor IoT Edge modules at scale by using the Azure portal](how-to-deploy-at-scale.md) or [the Azure CLI](how-to-deploy-cli-at-scale.md).