A tenants power of attorney executing a lease?

[Chuck B.]

Dear BP landlords,

 I know very little about power of attorney. I know that if I search on it there's far too many power of attorney purchase deals to find any results here in the forums that relate to just a lease...

My situation is I have a potential tenant who is newly crippled and cannot move their hands. They are in the process of assigning power of attorney to a relative. They want to execute a lease with me but I know literally nothing about how power of attorney works in these cases or if there are any gotchas that I should be aware of.   

Anyone have any advice or tips?  Can the relative with power of attorney just sign on their behalf?  Do I need a notary?  

Any help is much appreciated!

Best,

  - Chuck