finding game objectS with tag as recttransform

I have a problem about finding objectS. I need to find some UI buttons and make them last sibling. The problem is that SetAsLastSibling () function is property of RectTransform. Is there any way to find them as recttransform with tag or get recttransform component?

public class SilahYerlestirme : MonoBehaviour {

    public GameObject[] silahKoymaTuslari;

    public void SilahPanelAcma (....)
    {
	    silahKoymaTuslari = GameObject.FindGameObjectsWithTag ("SilahKoymaButtonTag");

	    foreach (GameObject item in silahKoymaTuslari)
	    {
		    silahKoymaTuslari.SetAsLastSibling ();
	    }
    }
}

I am sorry about my English and thanks for your help.

public class SilahYerlestirme : MonoBehaviour {
public GameObject silahKoymaTuslari;
public void SilahPanelAcma (…)
{
silahKoymaTuslari = GameObject.FindGameObjectsWithTag (“SilahKoymaButtonTag”);
foreach (GameObject item in silahKoymaTuslari)
{
item.GetComponent().SetAsLastSibling ();
}
}
}