Format All Rows Where 1 Column Meets Condition

I'm trying to Multi-Select rows in order to format all rows, in "One Step" if the cell in col. "A" = 1. I managed to write the hereunder code but I'm still frastrating because I don't like the first RNG setting command. How can I avoid declaring RNG as row(1) and still be able to run the code. I assume I need some other Range set for RNG which, unfortunately, I could'nt find and the command I used includes row1 in RNG although cell A1 = 5.

Sub Conditional_Multi_Rows_Select()
Set RNG = Rows(1) ' this is my problem
LR = [A65536].End(xlUp).Row
For R = 1 To LR
If Cells(R, 1) = 1 Then
Cells(R, 1).EntireRow.Select
Set RNG = Union(RNG, Selection)
End If
Next
RNG.Select
Selection.Font.Bold = True
Selection.Font.ColorIndex = 3
End Sub

I had in mind to use:

Set RNG = Rows(65536)
but this will not make it a "neat" vba code, either.