Hi Yann,
I use the script below so I don't have to specify the details each time I save the pdf.
- Create a journal
 - Send my graphs to the journal
 - Add a save pdf button which has my preferences specified (you will need to experiment with the margins and scale factor)
 - Press the button to generate the pdf
 
Note: if the folder for the save location doesn't exist or JMP can't write to it the script will fail but not warn you.
Use: Current Journal() << Append( H List Box( Page Break Box(), ) to start a new page.
Regards,
Stephen 
//set file properties 
//(if location doesn't exist or JMP can't write to it the script will fail silently)
SaveLocation = "C:\Reports\";
Author = "My Name";
Title = "My Report";
//Create a journal to recieve the output
ResultWindow = New Window( Title, <<journal );
//add output
Current Journal() << Append(
  Graph Builder(
  Size( 534, 500 ),
  Show Control Panel( 0 ),
  Variables(
  X( :Prototype ),
  Y( :Name( "Sucre 1/3 [%]" ) ),
  Y( :Name( "Sucre 2/3 [%]" ), Position( 1 ) ),
  Wrap( :Voies )
  )
  )
);
//add a save button to the Journal Window
Current Journal() << Append(
  H List Box(
  Button Box( "Save As PDF",
  thisWin = Current Window();
  thisWin << Set page setup(
  margins( 0.4, 0.4, 0.7, 0.7 ),
  scale( 0.7 ),
  portrait( 1 ),
  paper size( "A4" )
  );
  thisWin << Set Print Footers(
  Author/*left*/,
  "&d;"/*center*/,
  "Page &pn; of &pc;"/*right*/
  );
  path = SaveLocation || title || Char(Long Date( Today() )) || ".pdf";
  thisWin << Save PDF( path );
  ), 
  )
);