How to Put Double Quotes (Quotation Marks) “” in Excel VBA?

I find the easiest way is to double up on the quotes to handle a quote.

Worksheets("Sheet1").Range("A1").Formula = "IF(Sheet1!A1=0,"""""",Sheet1!A1)" 

Some people like to use CHR(34)*:

Worksheets("Sheet1").Range("A1").Formula = "IF(Sheet1!A1=0," & CHR(34) & CHR(34) & ",Sheet1!A1)"
A Sample on my VBA for how to deal with double quotas

In this sample, the formula will check if D2 contains a space or not, Like ” ” and then decide which calculation to apply.