So after being with a few providers, it has become apparent that I am on the "thick" side - yes, I'm thick in the head, but I'm talking about another part of my anatomy.  I was with a local provider this past weekend, and she could barely get the cover on.  Needless to say, it makes for a less than satisfactory experience.
So my question is; Is it appropriate to ask the provider to bring a larger size cover, i.e. magnum?  Certainly, I would not do this as part of the initial request, but maybe in a follow-up e-mail.  I don't want to scare anyone off, particularly someone I haven't seen before, but would this be a reasonable request?
thanks.

Buy some Female condoms. Walgreen's has them or you can order them online. The condoms are big and should accommodate bigger guys. Good luck.

Also, it is not a good idea to mention condoms prior to your meeting as that could spook the gal into thinking you are LE.

Some ladies like myself cannot handle thick cocked guys and I would respectfully pass or if you didn't let me know beforehand (and this is something not unknown to you), I would have to restrict certain activities.  

Hi!  I certainly respect your right to have your own preferences and limitations on cock size.  BUT: there's another good reason to always stock some magnums.  Some guys find it very difficult to maintain an erection with a tight fitting condom.  A magnum is preferred.

that is the easiest solution.

out of the norm that you would want to know ahead of time...
I've had some tight fits, but never been refused intercourse - never thought to address this before hand because it would just seem a bit too much to talk about my junk like this.
Actually, if I lady couldn't handle a Magnum, perhaps she could hint at this on her site too, thus minimizing the chance of a "large" guy showing up.

If a guy gets comments on the size of his junk and some ladies have a hard time with it or he is disappointed that some ladies can't take it, then he might want to consider mentioning it in a discreet fashion.  

I think that most of the erect cocks that most clients have seen are in porn, and this results in many guys thinking that they are average or smaller than average when they aren't. I've seen many cases in reviews where the reviewer remarks that he is surprised that the provider thinks that he's large. In my own case, I was surprised when a provider pulled out a magnum for me, because I always thought that I was just average. I now find that I prefer "large" condoms that are a bit smaller than the magnums.

I was not very "experienced" before my entry into this world. I thought I was perhaps average at best or maybe a little under - even with knowing that porn guys are exceptionally big.  That can really warp your perception.