How to ask a professor to introduce other professors to me when he mentions that he has no funding? When asking for an opportunity to do a PhD with a professor at a US university, he replied:


  Excellent background. Unfortunately, I do not have funding to support
  new students. Good luck!


Now I want to tell him:


  Thank you for your time and consideration. Please keep me in mind if a funded position opens up in the future.


and I want to add that if there is any other professors that he can introduce to me in order to ask them for a PhD position.
What should I say?
Don't ask the professor for contacts to other professors where you could apply - there's a risk that he will perceive it as annoying, and in principle it is work that you could easily do on your own.

Instead, you could add something like the following to your response:


  Please feel free to forward my documents to any colleagues who could be interested in working with me.


This will put the professor more in a mindset of helping some colleagues to find a (hopefully) good student, which he might be more willing to consider instead of helping a random applicant to find another job opportunity.