Regex: letters dot and space only

Hello expert,

have an input field which should accept only letters, '.' and space (see image below). here is my code so far.

FIND FIRST OCCURRENCE OF REGEX '[^a-zA-Z]*' IN makt-maktx.

IF sy-subrc = 0.

MESSAGE e012.

ENDIF.

makt-maktx is the field on screen.

Help please