The 13 teams are:

Bradford & Bingley 2nd XV
Driffield 2nd XV
Harrogate 2nd XV
Huddersfield 2nd XV
Hull 2nd XV
Hull Ionians 2nd XV
Malton & Norton 2nd XV
Otley 2nd XV
Sandal 2nd XV
Scunthorpe 2nd XV
Sheffield 2nd XV
Sheffield Tigers 2nd XV
Wharfedale 2nd XV

A Google Map showing all 13 clubs is available at http://www.tinyurl.com/yrfuprem12-13