Is risk/reward ratio the key to making money in future trading? How can I know the potential reward?

No.

For example, if you have a 75% win rate, but you win $0.50 for every $5 you lose, it will be a matter of time before you blow up your account. As you can see the win rate is only part of the winning combination.

The risk/reward ratio should be combined with the win/lose rate. At the end of the day, if you aren’t able to make good trades, the ratios and other numbers won’t really matter.