So, the ID/SID combination is what determines the shininess of your Pokémon. If you're trying to capture Pokémon with perfect IV's and non-shiny, you don't need your SID for anything. If you want shinies but not flawless, you can use your SID to figure out shiny spreads in your game. If you want shiny AND flawless either you breed (using your ID/SID combination to figure out shiny seeds) or you have to abuse your ID/SID combination when you start a new game to be able to capture shiny flawless Pokémon.
So, lets stick with capturing non-shiny flawless Pokémon. Have you downloaded RNG Reporter and PokéRNGDP?
i already have RNG reporter but pokeRNGDP... i dont have it where can i download it? and after i downloaded it, what the next thing to do?