I'm using version 9.2.

                        <r:ApplicationMenu.FooterToolbar>
                            <r:ApplicationMenuFooterToolbar>
                                <r:ButtonTool Id="Options" Command="{StaticResource Options}"
                                              Caption="Opt_ions" SmallImage="/Images/Small/Options.png">
                                    <r:ButtonTool.ToolTip>
                                        <r:XamRibbonScreenTip Header="Options" />
                                    </r:ButtonTool.ToolTip>
                                </r:ButtonTool>
                                <r:ButtonTool Id="Exit" Command="{StaticResource Exit}"
                                              Caption="E_xit" SmallImage="/Images/Small/Exit.png" Margin="8,0,0,0">
                                    <r:ButtonTool.ToolTip>
                                        <r:XamRibbonScreenTip Header="Exit" />
                                    </r:ButtonTool.ToolTip>
                                </r:ButtonTool>
                            </r:ApplicationMenuFooterToolbar>
                        </r:ApplicationMenu.FooterToolbar>

Also please notice the Margin property (which should really be set in the theme).