Click the swap/deposit checkbox at the top of the website which will reveal a BTC option in the From box.
This feature is still in Beta so it is recommended to test with a small amount first. The fees include a 0.10% fee that goes to renVM, a Curve swap fee of 0.04% as well as the cost of a Bitcoin transaction (which is around $3 at the time of writing).
Check your Ethereum address is showing and then click the Swap/Deposit and stake button.
This will reveal a Bitcoin address further down the page. Send the amount of Bitcoin you specified to this address and wait until your Bitcoin transaction gets six confirmations (around 1 hour).
Receiving your wBTC or sBTC
After getting your six confirmations, you will get a prompt from Metamask or your favourite web3 provider to confirm a transaction.
After confirming it, you will receive your tokenized Bitcoin and see the following screen:
At this point, you should see your wBTC or sBTC in your wallet. Please note, Metamask doesn't show amounts below 0.001 so if you have an amount like this, you may need to check your balance has arrived on Etherscan.