Need to set size for User input textfield.

Hello, We have integrated our salesforce application with onespan using APEX SDK for our signature use cases. During our signature request, we need user to input their tax number, for that we are passing following expression which works fine: {{*esl_TaxNumber:Signer1:textfield:value("")}} But, we want to send size property to this text field, we used the below expression which didnt work: {{*esl_TaxNumber:Signer1:textfield:value(""):Size(80,20)}} Thanks Anway Kabir