Metamask: Add Binance Smart Chain (BSC) Network
Guide to add Binance Smart Chain (BSC) Network on Metamask (Desktop & Mobile)

MetaMask Settings
1) Go to settings page

MetaMask Settings
2) Click on Networks > Add Network

MetaMask Custom Networks
3) Key in the relevant details:
For more information on how to use MetaMask with Binance Smart Chain (BSC), you can check it out here.