how to change the height of a header

Hello Danny, 

You can change the height of the headers or tabs of a radPageView by code. You can use the properties ItemSizeMode and ItemSize in the documentation. Here is the link: https://docs.telerik.com/devtools/winforms/controls/pageview/properties-methods-events

I am sending you a code snippet for example how you can change it.

this.radPageView1.ItemSizeMode = PageViewItemSizeMode.EqualSize;
this.radPageView1.ItemSize = new Size(80,150);

I hope this helps you.

Regards,
Maria
Progress Telerik