A range finder is a big help
Careful there, the mid priced range finders don't work as well as they are suppose to. Something like the Terrapin would work but there about 2 grand.
Not a lot to lock on on the prairie, I've found mil dots to be more accurate.
Just have to learn the size of the antelope, they are about 14.5 on the average from top of their back to the bottom of their stomach.
An example if on Mil Dot covers the critter, its about 415 yards, 1 1/2 mils its about 278, 2 mils its 208.
What I like to do is find my Max Point Blank Zero. Meaning the vital area on an antelope is about 8.5 inches. So I find a zero that I'm never more then 4 inches high or 4 inches low, so I don't have to worry about hold overs. That's about 275 yards for my rifle, I'm good to 350 yards with my PBZ. That's 1.2 mils.
Watch the wind.
People tend to over estimate the range of antelope. Reason being they are small, plus they'll be in tall grass.
As I said, unless you have a high quality LRF they don't work. Nothing to hit on as you can see from the below picture.