In order to add icons to features and amenities from property page must build CSS for each element using :nth-of-type() and before css  selectors .

!!! This workaround works only if is setup to display all features and amenities: http://help.wprentals.org/wp-content/uploads/2017/07/icons-to-features-and-amenities.png

Example:

First remove exiting icons using below CSS:

.features_wrapper .listing_detail i {
display: none;
}

Then add icon for first feature using  below CSS:

.features_wrapper .listing_detail:nth-of-type(1):before {
content: “\f2cd”;
font: normal normal normal 14px/1 FontAwesome;
}

For the rest of features and amenities must change number and css declaration for icon content.

For icons must use font-awesome: http://fontawesome.io/icons/