How to create a database with its associated resource using merge command ?

Simply by using the Resource option in a CreateDatabase instruction of [Actions] section in a merge.cpf file :

[Actions]
CreateResource:Name=%DB_IRISAPP_DATA,Description="IRISAPP_DATA database"
CreateDatabase:Name=IRISAPP_DATA,Directory=/usr/irissys/mgr/IRISAPP_DATA,Resource=%DB_IRISAPP_DATA
CreateResource:Name=%DB_IRISAPP_CODE,Description="IRISAPP_CODE database"
CreateDatabase:Name=IRISAPP_CODE,Directory=/usr/irissys/mgr/IRISAPP_CODE,Resource=%DB_IRISAPP_CODE
CreateNamespace:Name=IRISAPP,Globals=IRISAPP_DATA,Routines=IRISAPP_CODE,Interop=1