How to create landscape pdf document?

Hi,

I'm using version 1.2.0

I want to convert exel document into PDF.
how to make pages landscape? I tried to set the custom page size, but i cannot find any description about using this property in
COM Interface.

Delphi:

property UseCustomPaperSize: WideString;

in what format should be specified its value?Something like this: UseCustomPaperSize:= '100, 500'; //width, height ?