The Sense widgets are not resizable, but they look nice at the size they are.
The PDF app that comes with the Jetstream is PDF Viewer.
It allows you to highlight PDFs and write on them. You can choose the highlight color and ink color for your markups and drawing/writing. Nothing you can't do with a printed copy.
If you are looking for sticky notes and serious annotation, check out ezPDF or Repligo. Both are more robust. You can use the pen with both of those apps as well.
They are paid apps and cheaper in the Amazon Apps Market....
Hope this helps!