Samrong Kiat is a waterfall in Sisaket. It is not part of any national park or forest reserve so there is no entrance fee. There is at least one small restaurant selling snacks and drinks and some nice hiking around the small river.
View Samrong Kiat Waterfall น้ำตกสำโรงเกียรติ in a larger map
The below video is not mine. Just clarifying. 