First of all your salary must meet the requirements. Bank statements for the last six months with salary certificate. Then you will need a letter from the father authorizing her to come with you and that you have been granted legal custody. This must be certified by your government. If you are still with the father it would be better that he applies for the RP. If not have all the documentation as I mentioned with birth certificate. Your sponsor must fill a form for the labor department. He can help you