To use Ruler Protocol on Binance Smart Chain (BSC) just switch your wallet to BSC.
Transactions on BSC will use BNB token instead of ETH, for gas.
To add BSC network to your metamask or wallet, please follow the instructions given by Binance. This can be found here: https://docs.binance.org/smart-chain/wallet/metamask.html
Once you have added BSC, it will look like this: