US fastfood giant McDonald's has appointed Russ Smyth as president of the European unit of the company.   Smyth, 46, has extensive McDonald's management experience in Asia, Latin America and Europe. Leading the management team in Europe, Smyth will succeed Charlie Bell, who was recently named by chairman and chief executive officer Jim Cantalupo as president and chief operating officer for McDonald's. Smyth will report directly to Bell.