Skim currently provides 3 ways to go to directly to a specific page (menu widget, menubar, shortcut), but they all only use the page label. This can be problematic as the label is not guaranteed to exist or be unique, or it may be hard to input (utf-8). Please allow a method to go to the physical page number, i.e. the number x in the message "Page x of y" displayed in the status bar.
You can do that through a hidden preference. See the Wiki for details.