The Mishna Berura Siman 51 :1 says that you should kiss the 2 front Tzitzis when you finish saying Boruch Sheomar.
http://hebrewbooks.org/pdfpager.aspx?req=14170&st=&pgnum=155
1 - Why do we kiss the Tzitzis after Boruch Sheomar?
2 - Why only the 2 front ones?