In order to create a button in the property manager page, it is required to declare the property of delegate type Action.

The pointer to void function assigned to this property is a handler of the button:

using System;

public class ButtonDataModel
{
    public Action Button => OnButtonClick;

    private void OnButtonClick()
    {
        //Handle button click
    }
}

Visit bitmap button for more information of how to create button with image.