Решение получено.
.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity"
prefHeight="149.0" prefWidth="236.0" xmlns:fx="http://javafx.com/fxml/1"
xmlns="http://javafx.com/javafx/2.2" fx:controller="sample.Controller">
<children>
<Button fx:id="button" layoutX="39.0" layoutY="53.0"
mnemonicParsing="false"
onAction="#actionF"
prefHeight="43.5" prefWidth="159.0"
text="Click Me!"/>
</children>
</AnchorPane>
