Requirement
We have a custom suitelet page as follows where I need to add the summary box at the top right of the page.

Solution
Use the below code to set the summary box field at the top right of the page.
FORM.bodyFields.custpage_filter_summary = formObj.addField({
id: "custpage_filter_summary",
label: "summary",
type: serverWidget.FieldType.INLINEHTML,
container: "custpage_group_filter",
});
FORM.bodyFields.custpage_filter_summary.updateBreakType({
breakType: serverWidget.FieldBreakType.STARTCOL
});