A marking apparatus includes a selectively inflatable balloon. The balloon includes an external lumen adapted for connection to a vacuum source. The external lumen includes ports for creating a vacuum at the ports sufficient to draw walls of the gastric cavity into contact with the external lumen. The balloon is further provided with RF energy delivery devices. In accordance with an alternate embodiment, a marking apparatus includes an elongated, hollow body, the hollow body including a proximal end and a distal end. The hollow body includes at least one suction trough in which a plurality of holes is disposed to draw suction on tissue. The at least one suction trough extends along a substantial portion of the hollow body as it extends from its distal end to its proximal end.