Is there a general equation or formula for figuring the amout of
pressure in PSI that a wieght will exert on an object? For example, I
am 220 pounds, just standing still, how much force am I exerting on
the floor in PSI?

Hello.

The basic formula is:
pressure = force (in pounds) / surface area (in square inches)

To figure out the PSI of you standing on the floor, you'd need to
calculate the surface area of your feet in square inches.

This very question is addressed on the web page Global Science and
Technology Week: Ask a Scientist or Engineer:
  
"what's pressure in simple way? 
Pressure is the measure of how much force is applied in a confined
surface area. It is measured in pounds per square inch. To calculate
pressure use this formula:
 
pressure = force in pounds divided by surface area in square inches 
 
The smaller the area is the large the pressure will be.  
 
...Here's a question for you: What pressure do you put on the floor
when your are standing on two feet? On one foot? On tiptoe toes? Hint:
for the force, use your weight. For the area of your foot, cut out a
square equal to one square inch and count how many squares fit on the
bottom of you feet."
Source: Askvrd: Ask a Scientist or Engineer
http://askvrd.org/askNSF/knowledgedb.asp?cat=784&ques=2014


"If a man weighs 160 pounds, that weight, or force, is more or less
evenly distributed by the soles of his shoes. The area of the soles of
an average man's shoes is roughly 60 square inches. Each of those
square inches has to carry 160 ÷ 60= 2.6 pounds of that man's weight."
From FORCE AND PRESSURE, US Navy, cached by Google:
http://216.239.33.100/search?q=cache:XgawLgBqlOEC:https://www.advancement.cnet.navy.mil/products/web-pdf/tramans/bookchunks/14037_ch9.pdf&hl=en&ie=UTF-8&client=googlet

So let's suppose that your shoes are 80 square inches. Your PSI would
be calculated as follows:
220 pounds / 80 square inches = 2.75 PSI

search strategy: "calculate pressure", "pounds per square inch"

I hope this helps.