The park closes frequently due to flooding, check for closures before you head to it.
To get to the Red Buckeye Trail you should run along the White Oak Trail for less than a quarter of a mile. Look for the trail on your right/south.
The trail heads due south on a small peninsula formed between Big Creek and the Brazos River. The trail follows the edge of the creek and includes a small bend to the west. The trail then takes you near where the creek joins the Brazos River before heading north to follow the river back up to the White Oak Trail.