FormulaR1C1 to refer to workbook from text string

So i've got a little bit of a tricky problem here, i thought i had the right code but its coming out a little odd when i execute it, and i can't figure out why.

I'm attempting to create a macro which will open a prompt to select a workbook using the GetOpenFilename command, so far, so good. I then want to use the FormulaR1C1 command to refer to a specific cell (C2) within the targeted workbook. This is the code i'm currently using:

Sub AddNew()

Dim targetfile
Dim databook As Workbook
Set databook = Workbooks("Database.xlsm")
Dim iRow As Long
Dim ws As Worksheet
Set ws = Worksheets("Database")

targetfile = Application.GetOpenFilename("Excel Files (*.xlsm),*.xlsm")
    
databook.Activate

'Finds the next open row
iRow = ws.Cells.Find(What:="*", SearchOrder:=xlRows, _
    SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
    Cells(iRow, 1).Select

ActiveCell.FormulaR1C1 = "=' " & targetfile & "Summary'!R2C3"

End Sub

The last line of code is where i am running into trouble.

When i run the macro, the following string shows up in the next empty row.
='C:\Users\Alkuan\Documents\[Example.xlsmSummary]Example'!R2C3

The correct reference should be :
='C:\Users\Alkuan\Documents\[Example.xlsm]Summary'!R2C3

if i display the string 'targetfile' right before this step, it shows up as
C:\Users\Alkuan\Documents\Example.xlsm

Any guidance as to where i've gone wrong would be greatly appreciated!

Thanks in advance.

I found a very clumsy workaround that does work, but there has to be a better way.

Dim targetfile
Dim tempbook As Workbook
Dim databook As Workbook

Set databook = Workbooks("Database.xlsm")

targetfile = Application.GetOpenFilename("Excel Files (*.xlsm),*.xlsm")
    If Filename <> "False" Then
        Set tempbook = Workbooks.Open(targetfile)
    End If
    
databook.Activate

Dim iRow As Long
Dim ws As Worksheet
Set ws = Worksheets("Database")

iRow = ws.Cells.Find(What:="*", SearchOrder:=xlRows, _
    SearchDirection:=xlPrevious, LookIn:=xlValues).Row + 1
    
Worksheets("Calculation").Activate
Range("A1") = targetfile
targetfile = Range("A2")

ws.Activate
Cells(iRow, 1).Select
' Enters the link into the appropriate cell
ActiveCell.FormulaR1C1 = "='[" & targetfile & "]Summary'!R2C3"

Where the cell A2 in calculation has the following formula in place.

=RIGHT(A1,LEN(A1)-FIND("~",SUBSTITUTE(A1,"\","~",LEN(A1)-LEN(SUBSTITUTE(A1,"\","")))))

This returns the part of the string after the last '\'. Which in this instance is the file name. By inputting this into the cell when the referenced workbook is open, it automatically is converted into the full reference when the workbook is closed at the end of the code.

For example, if this string is input into A1. C:\Users\Alkuan\Documents\Example.xlsm
A2 returns, Example.xlsm

As i said, very clumsy and there must be a better way to achieve this.