To add USD1 to the metamask you need:
- In the wallet select the desired network and then in the cryptocurrencies section scroll to the bottom - click "Import tokens".
- Copy the smart contract address for USD1 from the list below.
- Paste into the "Smart Contract Address" field.
- Click the "Add Custom Token" button.
The USD1 is available on the 9 blockchain networks. Below is a list of USD1 smartcontract addresses to add to the metamask: