Toki works with Shopify POS through their seamless integration so you can allow your members to earn and redeem their store credit automatically. First, you will need to add the Toki blocks to your POS system. There are blocks for referrals as well as loyalty, most likely you will want to add both. 

Your store clerk will need to ask the user for their loyalty QR code to scan in order to verify they are who they say they are and give them their credit.

You can view this article to learn how to add the QR code to your loyalty wallet/account page.