Allow a ditamap/topic to use custom template instead of default one to generate PDF

Hi Guys, i am trying to create PDF as an output using a DitaMap and Dita topics in it. and I am able to achieve the same but want to change default template name (C:\Program Files (x86)\Adobe\Adobe FrameMaker 2017\Structure\xml\DITA\outputTemplates\ditabase.template) to custom template to generate pdf output.

so any idea, how can we allow a ditamap/topic to use custom template instead of default one?