I would like to apply for China Multi-Entry Visa with 6-months Validity.Can I send someone on behalf of me to apply for this application?

Hi,
I would like to apply for China Multi-Entry Visa with 6-months Validity.
Can I send someone on behalf of me to apply for this application?
If can, what is the requirements and documentations should I submit?
Should I issue the Authorization Letter for the person in charge on behalf of me (runner) to apply for this application?

Thank you in advance for your clarification.