About job NOC proof

[TADF chemist]

Hey I have 2 questions, please help:

1. I have worked in Canada as Chemistry Postdoc. I design, synthesize and analyze chemicals. What NOC code should I use?

2. Whom should I ask to write the proof of my work duties (i.e. list of work duties that matches vast majority of NOC requirements)? The HR manager or the direct supervisor (i.e. professor)?

Thanks