My employer made two contributions to an SEP account in my name. The checks were made payable to the investment company. Do I enter that amount on my taxes?

The SEP contributions should show on the W-2 box 12 code F.

The contributions were made after I received my W-2, so there is no code in Box 12; however, code F mentions a "...salary reduction SEP." The contributions were made in addition to my annual wages.  Also, would the code be in Box 12a, 12b, 12c, or 12d?

Box 12 has 4 lines indicated by a,b,c & d.   And if the contributions were made after the first of the year then they are probably 2019 contributions ... check with the employer.

@dmertz  can you weigh in on this ?

SEP contributions by an employer wouldn't shown on the W2, only the employer gets benefit of that.  
The employee doesn't recognize anything related to the SEP on their tax return.

Code F is for an employee's elective deferrals to a SARSEP established before 1997.  This is not an elective deferral to a SARSEP.

Yes ... I thought I was off base on that one ... thanks for the confirmation.

Thanks to all of you for your help!  Much appreciated!

The SEP contributions are employer contributions.  They are a deduction on the employer's tax return, not on your tax return.  They are not included in your income until you take them as a distribution from your SEP-IRA.