Here is an example that uses a sample application builder. I have JMP Pro, so I am not sure it will work.
However, if you know the name or can get a handle to the dashboard window you just created (see comment lines ) the rest of the script might work. Note you might have to scale your page to get the display you want.
Names Default to Here(1);
dbapp = JMP App();
dbapp << open file("$Sample_Dashboards/Six Quality Graphs Dashboard.jmpappsource");
dbapp << Edit Application;
dbapp << Run Application;
wait(0);
//__________________________________________________________
//get a handle to your dashboard using window list
//or dbwin = window("your title")
_xx = get window list( );
//should be the last window created
If( !Contains( _xx[nitems(_xx)] << get window title, "Dashboard"), Throw());
dbwin = _xx[nitems(_xx)];
myjrn = New Window("DashBoard Report", <<Journal);
dbwin << Journal( Freeze All);
myjrn <<Set page setup(
margins( .5, .5, .5, .5 ),
scale( .66 ),
portrait( 0 ),
paper size( "Letter" )
);
myjrn <<Save PDF("c:\temp\mypdf.pdf");
Screen capture of PDF file