Upbit, an exchange hosted in South Korea, makes it easy to buy $RFR. These instructions are for the English-translated version of upbit.com

Click the "Sign Up" button at the top-right of their home page. 

You'll need to create a "Cacao" ("Kakao") account. Click "Login to cacao account".

Agree to the terms and conditions to continue to the next page.

Add your information and create an account.

Once you're signed in, you can transfer funds on the “Disbursement” page, located in the top bar. You can use the green “Deposit” and “Withdrawal” links to connect your wallet addresses and transfer funds to the exchange.

Once you have funds, go to the “ExchangeInvestment” tab and use the search bar on the top-right to look for RFR.

Buying and selling is done in the middle of the page, near the bottom. Enter your order and click "Buying". Congratulations, you bought $RFR on Upbit!