You will want to stand on the line directly in the middle, of G/H-8. From there once you widescan, you should see a huge group of Smilodon, ignore the other ones, only focus on the giant group.
The 10th one
of that giant group of Smilodon, is the PH.
The PH usually spawns at the bottom quarter of G/H-7, so if the 10th Smilodon is in that general area, it's the PH. Remember to Flee once you've killed the PH, you will want to use that as a repop timer to know exactly when it will be back up.
If you want any additional information, see
here.