Looking on the internet deeply has found these results:

I am sorry to have kept you waiting is the most popular phrase on the web.

I am sorry for having kept you waiting 11,130 results on the web	I am sorry to have kept you waiting 119,500 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Forgive me for having kept you from your party. I am sorry for presuming, Mrs. Draper. Mr Staes, I am sorry for having left some of your questions out. I am sorry to keep you waiting. I am sorry for many things that are occurring in this kingdom. Mr President, I am sorry for having spoken for fully half an hour, but I feel that Parliament is entitled to a complete response to the many amendments tabled. I'm sorry to having kept you waiting. I am sorry for having bullied you... for having tried to force you... into the shackles of the family.	I'm sorry to have kept you waiting, but you're 20 minutes early. I'm sorry to have kept you waiting for a long time. I am so sorry to have kept you waiting. I'm sorry to have kept you waiting, but I had to explain to the Judge all the incongruity of your trial. I'm sorry to have kept you waiting... but there's been a slight hitch in the proceedings. I'm sorry to have kept you waiting. So sorry to have kept you waiting. I'm so sorry to have kept you waiting, Mrs. Myers.

I am sorry for having kept you waiting

11,130 results on the web

I am sorry to have kept you waiting

119,500 results on the web

More popular!

Forgive me for having kept you from your party.
I am sorry for presuming, Mrs. Draper.
Mr Staes, I am sorry for having left some of your questions out.
I am sorry to keep you waiting.
I am sorry for many things that are occurring in this kingdom.
Mr President, I am sorry for having spoken for fully half an hour, but I feel that Parliament is entitled to a complete response to the many amendments tabled.
I'm sorry to having kept you waiting.
I am sorry for having bullied you... for having tried to force you... into the shackles of the family.

I'm sorry to have kept you waiting, but you're 20 minutes early.
I'm sorry to have kept you waiting for a long time.
I am so sorry to have kept you waiting.
I'm sorry to have kept you waiting, but I had to explain to the Judge all the incongruity of your trial.
I'm sorry to have kept you waiting... but there's been a slight hitch in the proceedings.
I'm sorry to have kept you waiting.
So sorry to have kept you waiting.
I'm so sorry to have kept you waiting, Mrs. Myers.