You can do that in the catalog explorer: browse to the proc in the catalog explorer, click open the nodes, you'll find a node #0. Right click it, and select 'Change' from the context menu. then give it a value of 1 or 2.
You can also set the resultset parameter manually for more procs. Go to the preferences, and select 'SqlServerAutoDetermineSProcType' to false AND 'ManualSelectSProcsFromSchema' to true. These options are under 'Schema Element retrieval'.
You'll then get a popup, in which you can multi-select procs and set for all these procs the # of resultsets in one go. You can use a filter to select a lot of procs in one go to ease the selection process.