Drive east on HWY 518 from HWY 64 towards Talpa and Pot Creek. .8 miles after you exit the town of Talpa, watch for a sign that says "Rio Grande del Rancho Trail 18". There are small pull-offs on either side of the road.
Find the obvious start of the trail which is well marked. The first 1/4 mile is really steep and loose. Deal with that challenge and the rest of the trail will be quite easy in comparison. Follow the faded doubletrack south (right at the top of the hill) as it contours the foothills above HWY 518 and the Pot Creek Historical Cultural Site.
After about five miles, you get off of Trail 18 and onto a dirt road in a meadow. You can follow this dirt road over a river and hit HWY 518 at the 6.5-mile point or you can just make a u-turn and head back the way you came.
If you choose to go to HWY 518, you can back track on dirt the way you came, or take the highway back to your parking spot. This trail also makes a nice shuttle option if you don't want to run 10 to 13 miles.
Note: Pot Creek Cultural Site is worth a visit! It was home to the ancestors of the modern day Pueblo tribes before it was abandoned in about 1320 AD. Please remember to treat this area with respect, and do not touch or move any artifacts in addition to practicing other Leave No Trace principles.