Open your .sch file -> Preferences -> Component libraries
Add component library files and choose your .lib files from the project_libs directory.
- In project window, click new directory, rename it project_libs
- Add .lib files in this folder
- create project_footprint.pretty sub-directory in project_libs
- Add kicad_mods in this sub-directory
Now in footprint editor, preferences -> footprint libraries manager-> project specific libraries click on on "Append Library"
Example:
Nickname: project
Library path: ${KPRJMOD}/project_libs/project_footprints.pretty