Can a potential Supervisor leave a hint on you in the scholarships and influence somehow the selection? I wonder if a full time professor could somehow influence the scholarship committee. I know that my potential supervisor is currently recruiting PhD students, he told me when I first approached him. He has accepted to be my supervisor and we are in touch. How is he sure that he is gonna recruit the potential PhD students he has accepted to supervise? They may have 5 potential PhD students and none of them will get the scholarship.
I would expect that absent firm rules that professors lobby pretty hard for the students they most want. It isn't a question of leaving some subtle hint. 

There might be rules against it, of course, and that might dampen it down a bit, but ....

There might even be "horse trading" among senior professors. 

But it is just another form of competition. Having a professor strongly advocate for you doesn't guarantee much if other professors are lobbying for others and the money is limited.