In your case it is not "boneName", this was just an analogous reference in the SkeletonDebugWindow.cs file.
As I wrote above, in your case it is "animationName".
So the complete code for your class would be:
class YourClass {
...
public SkeletonRenderer skeletonRenderer;
...
[SpineAnimation(dataField: "skeletonRenderer")]
public string animationName;
void YourMethod() {
...
var animationProperty = new SerializedObject(this).FindProperty("animationName");
EditorGUILayout.PropertyField(animationProperty, new GUIContent("Animation Name"));
}
...
}