It should be similar to RadCheckedListBox:

DataTable dt = new DataTable();
dt.Columns.Add("Id",typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("IsChecked", typeof(int));

for (int i = 0; i < 10; i++)
{
    dt.Rows.Add(i,"Item"+i,i%2);
}
this.radCheckedDropDownList1.DataSource = dt;
this.radCheckedDropDownList1.DisplayMember = "Name";
this.radCheckedDropDownList1.ValueMember = "Id";
this.radCheckedDropDownList1.CheckedMember = "IsChecked";