To enable the included PAM module and allow use of the fingerprint reader
for instance to login via the SDDM login manager, add a 'pam_fprintd.so' line
right below the 'pam_unix.so' definition in '/etc/pam.d/sddm': like this:

auth    sufficient    pam_unix.so try_first_pass likeauth nullok
auth    sufficient    pam_fprintd.so

Likewise, immediately below 'pam_unix.so' add  a 'pam_fprintd.so' line
to '/etc/pam.d/kde' so it looks like this:

auth    sufficient    pam_unix.so try_first_pass likeauth nullok
auth    sufficient    pam_fprintd.so