Looking on the internet deeply has found these results:

please let me know if that is fine for you is the most popular phrase on the web.

please let me know if it is fine for you 13 results on the web	please let me know if that is fine for you 16 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Please let me know if he gets any worse. Please let me know if anything is uncomfortable. Well, I aim to pamper our VIPs, so please let me know if there's anything I can do for you. And please let me know if there's anything else you require. Well, please let me know if you do find it. Please let me know if any Peacekeeper scans are imminent. Please let me know if I can be of any further assistance, Mr. Mars. I hope this review is helpful. Please let me know if you need any further information.	Well, I aim to pamper our VIPs, so please let me know if there's anything I can do for you. Please let me know if there's any other way I can be of assistance. Please let me know if he gets any worse. Please let me know if anything is uncomfortable. Please let me know if I can be of any further assistance, Mr. Mars. And please let me know if there's anything else you require. Well, please let me know if you do find it. Please let me know if any Peacekeeper scans are imminent.

please let me know if it is fine for you

13 results on the web

please let me know if that is fine for you

16 results on the web

More popular!

Please let me know if he gets any worse.
Please let me know if anything is uncomfortable.
Well, I aim to pamper our VIPs, so please let me know if there's anything I can do for you.
And please let me know if there's anything else you require.
Well, please let me know if you do find it.
Please let me know if any Peacekeeper scans are imminent.
Please let me know if I can be of any further assistance, Mr. Mars.
I hope this review is helpful. Please let me know if you need any further information.

Well, I aim to pamper our VIPs, so please let me know if there's anything I can do for you.
Please let me know if there's any other way I can be of assistance.
Please let me know if he gets any worse.
Please let me know if anything is uncomfortable.
Please let me know if I can be of any further assistance, Mr. Mars.
And please let me know if there's anything else you require.
Well, please let me know if you do find it.
Please let me know if any Peacekeeper scans are imminent.