Ancestral allele data is provided to dbSNP as part of the SNP assay data that is provided in dbSNP submissions, so we don't have a program that allows us to annotate ancestral alleles, and we don't currently have a mechanism for third party annotation of SNPs.. If the ancestral state of the SNP in which you are interested is known, and is contained in dbSNP, look in the “Allele” section of the the RefSNP page, which is located at the top right hand side of the report.