I have 2 spreadsheets. How does one write code to have a specific cell in
one spreadsheet equal the value of another specific cell in a different
spreadsheet.

I understand the following works:
Sheets("Sheet1").Range("A1").Formula =
"=[SpreadsheetName]WorksheetName!R1A1"

but how does one point to a spreadsheet in a different location: (something
like below)
Sheets("Sheet1").Range("A1").Formula =
"=C:\SomeDirectory\SomeOtherDirectory\[SpreadsheetName]WorksheetName!R1A1"