You need to configure store locator group as described in this link https://technet.microsoft.com/en-us/library/jj728715.aspx and then configure longitude and latitude for your retail channel http://dynamicserppros.com/retail-inventory-availability-proximity-retail-store-dynamics-ax-2012-r3/
Hi, welcome to my blog. Do leave a comment if you find any post helpful or have suggestions. I have dedicated this blog to try to put solutions to some of the technical issues I faced as an application developer -Hitesh Manglani