You can access with the following link to the PowPeg App which allows users to select the Rootstock account where they want to receive the funds.
Additionally, users can check the status of their peg-in transactions within the app, making it easy to have an estimate of the time remaining until the funds are credited to the RSK account.
Go to the Rootstock PowPeg application page.

The switch at the top right allows you to switch from dark to light mode.
To swap from BTC to RBTC, you have software as hardware wallet options.
Before you start, you must accept the terms and conditions by clicking I acknowledge and accept terms and conditions.
Click on the BTC TO RBTC box.
When you log in, you can select either software wallets.

Or hardware wallets.

Once connected, you will see the screen to complete the exchange details.

Select the account type in the upper right corner, enter the amount (the minimum is 0.005 BTC), take into account the indicated commission (you can adjust it to slow, average, or fast), and connect the destination wallet in Rootstock.
Review the details of the operation. Then follow the instructions to sign the transaction in your wallet.
Done! After the estimated confirmation time, you will receive the RBTC.
Copy the transaction ID so you can review it later if necessary.
You can then use them to mint DOC or BPRO and start doing DeFi with Bitcoin.
The Peg Out process is as easy as the Peg In. Go to the PowPeg App.
Select the corresponding wallet:

The app uses one unified interface to guide you through the entire peg-out process. When prompted, input the required fields.
Keep in mind that you should check the Bitcoin on-chain fees. The 2way Peg app is meant for big amounts. The minimum accepted value is rBTC 0.004.
There's a method (getEstimatedFeesForNextPegOutEvent) to estimate peg-out fees on Rootstock's Github.
Otherwise, you can check it when you fill out the peg-out form.

You can check the Bitcoin destination address although this is optional. Then click Send and check the status of the transaction.