You didn't provide a denomination but the only 1928-series bill that was issued long enough to reach F (the small letter next to the date) was the $5 US Note.
Please see the Related Question for more information.
"F" is the highest series letter for 1928 $5 red-seal notes. Please check your bill again and see the question "What is the value of a 1928 US 5 dollar bill with a red seal?" for more information.
Please check again and post a new question. No $2 bills are dated 1929.If your bill's date is 1928, there's more information at the question "What is the value of a 1928 [letter] US 2 dollar bill?"
Please check your bill again and post a new, separate question. 1928 $1 US Notes were only issued in one series so there are no subseries letters.
what is the value of a 1953 two dollar bill with a red seal
"F" is the highest series letter for 1928 United States Notes. Please check your bill again and post a new, separate question.
Only coins are minted and have mint marks. Bills are printed. The F is called a series letter and indicates that the bill was the 7th signature combination in the series begun in 1928.Please see the Related Question for more information.
Please check your bill again and post a new, separate question. "E" is the highest series letter for 1928 $1 silver certificates.
Please don't assume that every old bill is a silver certificate. The banner across its top and the red seal indicate it's a United States Note, a form of paper money issued directly by the Federal government. US Notes were discontinued in the 1960s. There's more information at the question "What is the value of a 1928 F US 5 dollar bill with a red seal?"
Normally a date would be needed to identify your bill, but only the 1928 series of $2 bills had letters extending to F. Please see the Related Question for more information.
Sorry, there is no such bill.
Please check again and post a new question. The US didn't print any bills dated 1941. Only the 1928 series of $2 bills included an F series letter.
Please see the attached link.