You'll want to make sure you're running the very latest rancher as some of the drivers were recently added. Go to the API & Keys screen in the UI (under the user circle in the top-right corner) and click on the API endpoint. Then click on the "machines" link, and click the blue Create button. This will show you the inputs for creating a machine. There's a drivernameConfig input for each driver, vmwarevsphereConfig and vmwarevcloudairConfig should be two of them.
To create a machine you'll need to construct the config as JSON since the API UI doesn't support nested complex objects yet. Clicking on the config's type will bring you to the schema which tells you about the fields it has (/v1/projects/1a5/schemas/vmwarevsphereConfig). For example, vmwarevsphereConfig takes:
"boot2dockerUrl", "computeIp", "cpuCount", "datacenter", "datastore", "diskSize", "memorySize", "network", "password", "pool", "username", "vcenter"
which should correspond to the options you can pass into the docker-machine CLI.
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Vincent