The link you suggested above is to create rating system manually..but you see in our last ticket you have suggested to create a toolset number field. So I have added field using add meta and I am asking you that how to add filter using that field.
I have added meta using wpcf- prefix in plugin file.
I understand that but you can not enter filter using star images etc..etc..
You can enter normal filter either by dropdown with values or as radio buttons with values. To style the filter with star images you need to follow the link I shared with you.