What is the best way to transpose a recorded minus one song?

I have a minus one audio track that needed to be transposed down 2 semitones so that the singer can sing the song comfortably. I had tried process > transpose> check transpose audio> choose radius mix advance. But I don't know how to set the radius pitch and radius phase setting. The manual does says anything about this. The transposed song does have some minor artefacts.
 
Anymore here in the forum can advice? 
 
Thanks ahead of time.

Thanks CJ.
               How can I set V-vocal to transpose the audio down by 2 semitones? And what about the formant setting? I am still very new to v-vocal.
 
Choo Shi-Hwei

Or, you should also have the Cakewalk Pitch Shifter plugin in your effects arsenal. I've used it with some success in the past (depending on what you're transposing and by how much of course.)