Set Custom sitemap target audience

I have created a custom SiteMap for the navigation in Sharepoint 2010. I am calling this SiteMap in my custom MasterPage. Everything is working fine.

Now I want to add the target audience in my custom SiteMap.

As we know that using the default navigation which is present from the Site setting > Navigation, we can set the Target audience. But in my custom SiteMap, I have to set the target audience, and I don't have any option there.

How can I set the Audience in my Custom SiteMap?