SoundTouch in SynthesiserVoice class

Hello,
I just wonder. I have my SynthesiserVoice. I can’t use pitch shifter in my PluginProcessor class, because each sound has its own pitch knob. So my idea is to use it inside SynthesiserVoice class.

Do you have ideas or examples how to insert soundTouch to renderNextBlock method?
Because my attempts were not successful.

Thank you