A TOURNAMENT doctor at the French Open gave Swedish player Henrik Holm a scare as he prescribed a throat medication containing a banned substance. Holm, who complained of a sore throat, was given a spray by tournament doctor Bernard Montalvan. But the player's coach, reading the label, noticed that the ingredients included a substance which is included on a list of illegal medications and which could lead to a positive doping test. The French doctor seemed remarkably blase about his grave error. ''I gave him the spray because he complained of a sore throat,'' said Montalvan. ''The banned ingredient was in such a low dose, that it is not likely that it would be found in a dope test anyway. ''If he had tested positive I would have shown the note which I wrote telling him how to use the spray. ''But I guess that if he'd been caught, I would have had to take some responsibility.''