Primer Design - how to choose primer for SNPs in Primer 3

Question

[Human]

hello folks,

So, I want to design a Primer for SNPs in Primer3.

Should my Primers "flank" the SNP ? So, should I but my SNP within the sequence in " [ ] " ?

Or should I choose that Primers must overlab the junction, so put my SNP between "- -" ?

Thanks for any help