How to add Authorization lambda to serverless-apigateway-service-proxy?

Serverless Framework
1

How to reference authorization lambda function when using the GitHub - serverless-operations/serverless-apigateway-service-proxy: This Serverless Framewrok plugin supports the AWS service proxy integration feature of API Gateway. plugin?

authorizationType : “CUSTOM”
authorizerId : { Ref : “ApiGatewayProxyAuthorizer” }

functions
authorizer:
handler: common/labda-authoriser

What should I put into the authorizerId?