Hi

First of all you have to screen and amplify your samples with the RAPD primers. Once you screened your samples and have good and reproducible banding pattern with few selected primers  you have to amplify the bulk of samples. For developing SCAR you have to identify the samples with the unique band/ fragment which is not present in the other samples. For example male female characterization of any species. You choose 10 male and 10 female individual plants and amplified all the samples with the RAPD primers. Now you have to check which is the characteristic band/fragment present in male but absent in female and vice vera. Slice/ elute that band/fragment  from the gel, isolate the DNA and purify it using appropriate protocol followed by sequencing with that RAPD primer. Once you obtain sequence, use these sequences for primer development and validate them in the same species. Once they are validated, these primers are the SCAR markers for that species.

Good luck

I agree with Arun.

thanks for the followup comments Arun and Mostafa

Dear Aheibam

Please take a look at the following articles.

Thank your very much @Seied