Haplotype Reconstruction using PHASE

Question

[evo_genomics]

I am new to this field so my question is quiet naïve and stupid. For my data set, it look likes one snp of my gene of interest is under selection. I want to apply the ihs/ehh but before applying it, I have to reconstruct the haplotype. As I am interested in only one snp how should I select snps for haplotype reconstruction and how many snps should be selected? I am using PHASE for haplotype reconstruction.

Thanks