The 'Percent of Ownership' designates your share of the amount of rental or royalty income you are reporting. Generally, what is reported to you has already been divided and you receive only your portion. If this is the case, you will report 100% as the percent of ownership. The program will calculate the income reported by multiplying the percent of ownership by the payments received.
Steve has a 3% ownership stake in a property being drilled for oil. He receives a royalty check and statement for $150. He should input his percent of ownership as 100% and claim the $150 royalty. This is because 100% of his check belongs to him, his portion had been pre-determined.
If you select an amount other than 100%, the program will calculate your amount of income and expenses based on the percentage entered. Depreciation is calculated based on the percentage of business use entered into the program.