If he's chasing right now there's not a whole lot you can do. However, the rut for mature bucks is organized chaos, it may appear that he is just running around randomly after any doe, which is true to a certain point. But chances are hes already targeted his does travel routes and should be running those back and forth, semi-consitentley. Like i said its organized chaos for him so try to locate his bedding area; both at night and in middday to see if you cant intercept him there. If no luck there, try some soft contact grunts, a bleat-in-heat call, or some estrous scent to lure him in, cause chances are if he's near by, one of those 3 strategies SHOULD catch his attention enough to raise his curiousity level. Hope all this helps, good luck, and let me know if you get him!