Have a direct paternal line descendant of Smith Alexander Stills take a Y-DNA37 test from Family Tree DNA. Also have a male with the Ricker surname who is related to Uriah Ricker take a Y-DNA37 test. If they match each other on about 35 out of 37 markers or closer then that is very strong evidence those two direct paternal lines share a Ricker ancestor. However there remains a slight possibility the Ricker you test was not really the son a Ricker. Few things in life are perfect ;-)
If two male direct paternal line descendants are not available then there is autosomal and X chromosome testing you can employ but it is more difficult.
WIkiTree also has a new DNA feature - The Ancestor Confirmation Aid http://www.wikitree.com/wiki/DNA_Ancestor_Confirmation_Aid
which identifies which descentants should take which DNA test in order to confirm a particular ancestor.