I would create an account with Manageflitter and/or Followerwonk - both integrate with Twitter.
I know that many people feel negatively about Twitter but here's why it's great, especially for your quesiton:
There are no privacy settings.
Facebook and LinkedIn have tons of walls you run into while cruising around looking for potential buyers. And the other social networks are not conducive to time-effective/cost-effective networking for other reasons.
With these tools (Manageflitter and Followerwonk), you can search the bios of Twitter accounts for DPC, TPA, and any other relevant keyword. You can search within your location, or throughout Twitter as a whole. From there, the tools allow you to classify (List) or interact (Follow) them.
After that, I'd encourage you to engage them subtly, by favoriting and retweeting a few of their Tweets over several days.
Then begin a conversation with them, ideally about a mutual interest or some random thing they specify in their bio.
After a back-and-forth tweet or two, bring up your services tactfully. Ask them honestly if they need what you are offering. If they don't, maybe they know someone who is.
At the very least, you'll have a relevant networking partner/friend!
Another very valuable use of your time would be to post in LinkedIn groups. They are more professional than Facebook groups, and it's common for people to post jobs and other networking opportunities there, as well as pitch their own services. (See the lengthy URL at the bottom of this answer for an example).
Hope that helps - I'd love to talk more; there are several other ways you could go about connecting with DPC's and TPA's online.
This completely depends on who you are. Are you a physician with primary care experience? Are you a business person trying to build a concierge service network? I think the key issue in selling health services or any health product right now is value. Can your network deliver a BMI reduction of 7% to your client within 12 months? What kinds of patient population do they deliver services to? Are they affluent yuppies? Or are they working class prediabetic smokers? What technologies will your network leverage to provide better care? An Emr going to mu2 is not near enough. What app platforms does your network encourage? How will you price your services?
A general piece of advice is to utilize exclusively inbound marketing and once you have an MVP, you can ask questions and engage potential customers on your blog. Push marketing is futile. Join linked in groups with your pertinent end customer and ask questions rather than trying to make assumptions about what the tpa needs! Quite a general answer but hope it helps!
DPC and TPA are very different. Most large traditional insurance companies now act as more of a TPA as purchasers/employer groups bear the financial risk for health care and use "insurance companies" to act as a TPA. Typically the TPA will have a strategy to health, quality, and financial management they bundle as a product. Wellness services are part of the product. You need to figure out how to become part of the wellness service strategy and demonstrate your value to a TPA. This could involve performance guarantees, risk based contracting etc. Happy to talk more to help you frame this as an offering/pitch to a TPA.