If I register and use TNG RFID Tag, can I request for auto-reload function as well?

Yes. You would have to set up auto-reload function via your Touch ‘n Go eWallet app.

Steps as below:

1. Launch your Touch 'n Go eWallet app
2. Click Reload eWallet
3. Click “Auto-Reload” at the bottom right of the screen
4. Key in your auto-reload preference and you no longer have to worry about low balance again!

Please refer to article How do I activate the auto-reload function? for more info

Below are the articles that may be useful for you :

What are the differences between SmartTAG and TNG RFID Tag?

Where can I purchase TNG RFID Tag?