Where to put the "reduce" to run "molprobity"?

The reduce executable is downloaded from MolProbity/reduce at master · rlabduke/MolProbity · GitHub
Is this the correct reduce executable?

I have put it in my working directory with the pdb file, but running
~/software/haddock-tools/molprobity.py 4G6K-clean.pdb
got the error of not finding the reduce executable:

## Executing Reduce to assign histidine protonation states
## Input PDB: 4G6K-clean.pdb
Traceback (most recent call last):
  File "/home/lanselibai/software/haddock-tools/molprobity.py", line 137, in <module>
    hadded, process_error = run_molprobity(open_fhandle)
  File "/home/lanselibai/software/haddock-tools/molprobity.py", line 58, in run_molprobity
    reduce_exec = _check_molprobity_path(molprobity_executable)
  File "/home/lanselibai/software/haddock-tools/molprobity.py", line 47, in _check_molprobity_path
    raise Exception("Could not find path to 'reduce' executable: Are you sure it is installed?\n")
Exception: Could not find path to 'reduce' executable: Are you sure it is installed?

Make sure it is in your path

Thank you, after adding reduce to the PATH, running the molprobity.py got this error:

$ ~/software/haddock-tools/molprobity.py 4G6K-clean.pdb
## Executing Reduce to assign histidine protonation states
## Input PDB: 4G6K-clean.pdb
Traceback (most recent call last):
  File "/home/lanselibai/software/haddock-tools/molprobity.py", line 137, in <module>
    hadded, process_error = run_molprobity(open_fhandle)
  File "/home/lanselibai/software/haddock-tools/molprobity.py", line 69, in run_molprobity
    tmp_file.write(cmd_stdin)
TypeError: expected a string or other character buffer object

Try running first reduce manually, just to make sure it works fine.