ultimate member custom fields

Hi,
I have installed this plugin and ultimate member plugin. I want to add a search form for custom fields of users registered by ultimate member.
In details, I create a registration form with some custom fields for example state, city, education degree and so on. Now, I want to create a search form in which users can select the state and degree from drop-down menu and see the results.
I selects um_directory and um_form in post type, but, i do not know which meta key should be selected. There is a large number of meta keys start by um! ??
Can you somebody help me.

Thank you