Is onboarding the channel partner's responsibility? How do I get involved?

The channel partner will onboard them to their company. They’re not necessarily going to “onboard” them to every vendor they represent. You want to onboard a new salesperson when they arrive because it’s your chance to drive their attention and enthusiasm to your products over others. They’re also your salesperson now. Make the investment of onboarding them. Otherwise, you’ll never get as much sales performance out of them as you could have.