How to add custom op in tflite-runtime? Encountered unresolved custom op: FarthestPointSample.

[kuangzy2011]

Did inference with tflite-runtime, and got following errors.
Seems need to add custom op in tflite.
Any one can help?

 20 interpreter = tflite.Interpreter(model_path="./model-sign/model_sign.tflite")

---> 21 interpreter.allocate_tensors()
25 input_details = interpreter.get_input_details()

File /opt/conda/lib/python3.10/site-packages/tflite_runtime/interpreter.py:531, in Interpreter.allocate_tensors(self)
529 def allocate_tensors(self):
530 self._ensure_safe()
--> 531 return self._interpreter.AllocateTensors()

RuntimeError: Encountered unresolved custom op: FarthestPointSample.
See instructions: https://www.tensorflow.org/lite/guide/ops_custom Node number 0 (FarthestPointSample) failed to prepare.Encountered unresolved custom op: FarthestPointSample.