This description refers to the APT process. Similar points apply when using the Doubler process, but only one Pro Tools track is captured.
Select a suitable RVP preset from the drop-down Preset menu.
Select the audio in Pro Tools to be used as the Guide (if you haven't already done so) as shown below.
Click Capture Guide in the plug-in window (orange arrow 2 shown below). This will send the selected audio to the Revoice Pro (RVP) Session.
Select the audio in Pro Tools to be used as the Dub.
Click Capture Dub in the plug-in window (orange arrow 4 in the plug-in window above) to load the Dub audio into RVP.
An APT process track is automatically created in the RVP session, with the preset settings you chose.