Ronaldo has found the net 71 times in 138 international appearances while leading the team to their first senior international title at Euro 2016, athough injury forced him off in the first half of the grand final victory.
Despite the 32 year-old's achievements – which include four Ballons d'Or, three Premier League titles, a hat-trick of Champions Leagues and LaLiga glory in 2011-2012 – Santos thinks he is not recognised with the appropriate merit in his homeland.
"Sometimes I don't understand how we Portuguese sometimes value Cristiano so little," Santos told reporters.
"In qualifying for the European Championship and after the first games of the finals it was said he did not score goals, that he would not open the floodgates.
"Then, when he started scoring goals, we saw the other side.
"But Cristiano Ronaldo always scores. I've known him since he was 18 and he's always been the same, he's always scored and will continue to do so."