how do i check to see if the ignition is getting 12 volts on a ford f150 SB crewcab

First thing is to have the battery tested and check the battery and starter connections. These connections need to be absolutely clean, tight and free of corrosion.

Yes thank you I did that and everything that should have a good 12vkmt connection does. So now what should I check for because I'm at a loss here and not sure what to D next

If all cables are clean and tight and battery is fully charged, bypass relay at the firewall, if it still doesn't start, check voltage at starter big cable, u should always have 12.4. If voltage is good, check voltage at small wire on starter when someone turns ignition switch to start position, if voltage is present, replace starter. If no voltage present, trace back to neutral safety switch