Some people get frustrated when they apply mathematical measurements and formuilas and they don't get a signal. It's better to go off the actual signal than off the theoretical of where the signal is supposed to be.
You don't need a satellite finder, because the Manhattan receiver has a "beep" function. I have a Manhattan and this is how I do it:
First, get a pair of wireless radio frequency headphones (fifteen bucks Harbor Freight) . Set your receiver up where it will ultimately be. Connect to your LNB in the manner described in your LNB instructions.
Remember that the "due south satellite" language is inaccurate for most people, who do not live on the exact same longitude as where the satellite orbits. For the vast majority of us, the more accurate term is "southernmost".
Get your exact longitude. Go to the satellite list on this or other sites. Find the satellite closest to your longitude that has an active transponder. Go to your transponder list for that satellite. Make sure all numbers for that transponder are entered. Add that transponder. Make sure "beep" function is enabled. Go to "Single Satellite Search". Set it on the transponder you just entered.
Go to your dish. By whatever method you figure out ( I use a big framing square on mine) , get your dish to zenith position. This will be the position that the dish will be in when it is pointing at your exact longitude in the sky (where there likely won't be a satellite). Note the exact number of degrees between your exact longitude and the longitude of the satellite you are using for your southernmost. If it's say a degree and a half east of your longitude, if you have a dish mover, maybe you do about ten clicks east. You don't use your dish mover after that.
Then, with your receiver on and your headphones on and connected to the audio output of the Manhattan, and with your receiver set to the exact satellite and transponder you entered, by hand,you move the dish up and down and around the pole until you get a beep signal in your headphones. When you get the strongest signal, that's where you lock the dish in.