When merging onto a roadway from a private path, it is essential to do so at a **speed that allows you to yield** to vehicles already traveling on the roadway. This is crucial to ensure the safety of all road users.

- **Yield**: When entering a road, you must ensure that you do not become an obstacle or pose a danger to vehicles already in motion. This means you must be prepared to stop if necessary until you can merge safely.

- **Appropriate speed**: The speed when merging should allow you to observe and react to existing traffic. It is not about immediately matching the speed of vehicles on the roadway, but about doing so safely and progressively.

- **R.S.M. safety rule**: This rule emphasizes the importance of observing, signaling, and maneuvering safely. When entering a road, it is essential to follow these steps to avoid accidents and facilitate smooth traffic flow.

Therefore, the correct answer is to drive at a speed that allows you to yield to vehicles already on the roadway, thus ensuring a safe and risk-free merge.