To test REST API, you can skip adding the API to the ReadyAPI Test project and create a load test directly from a URL:
Right-click the project in ReadyAPI and select Create Load Test, or click
in the toolbar.In the New Load Test dialog, switch to the Manual tab and select the URL option.
Enter the name of the new test and the target URL.
Click OK.
ReadyAPI will create a REST request based on the specified URL, then create a new functional test with a REST Request test step, and then create a load test.