How to add current user to custom multi user filed in a post function

[Former user]

I need to add a current user to list of users stored in a custom field upon a transition. I tried the following: The following parsed text will be copied to Reviewed by: #Current user# and The following parsed text will be copied to Reviewed by: #Reviewed by#+#Current user#

Neither worked for me

License SEN: SEN-2732413

[Fidel Castro Armario]

To do it you can use two possible string to be copied into Multi User Picker field "Reviewed by": "+%{00020}" or "+%{xxxxx}, %{00020}" (removing double quotes), provided %{xxxxx} is the field code of field Reviewed by.