Hi Dimitri,
The SummaryTutorial sample demonstrates the creation of summaries through the designer. In the Properties window select TableDescriptor -> SummaryRows, then choose the Column against the DataMember for which the summary is needed, also choose the summarytype, format and display column. This will enable the summaries for the table and for each group that is created in the table.
Here is a path.
C:\Program Files\Syncfusion\Essential Studio\4.4.0.49\windows\Grid.Grouping.Windows\Samples\Summaries\Summary Tutorial\cs
Also refer to the below forum thread for editable summary.
http://www.syncfusion.com/support/forums/message.aspx?&MessageID=49541Best Regards,
Haneef