Adobe Reader lets you sign PDFs and incorporate that signature into the file. If you are viewing a PDF on the web, download the PDF first before you sign it.
Some documents have security applied that prohibits electronic signatures. In Adobe Reader Print such documents, save as a PDF and then sign the printed copy.

In CampLegal, click the Print icon to create a non-editable version of the PDF.
Click Fill & Sign in the right pane or choose Tools > Fill & Sign. The Fill & Sign tool's window is displayed.The Fill & Sign tool is displayed. Click Fill and Sign. Note: If you don't see this new Adobe Sign interface, update your Acrobat DC to the latest version. To automatically update from Acrobat DC, choose Help > Check for updates. Follow the steps in the Updater window to download and install the latest updates.
Click Request Signatures. The Add Signers option is displayed.
Do the following:
In the Signers field, add recipient email addresses in the order you want the document to be signed.
Change the default text in the Subject & Message area as appropriate.
Optional: If you want to add more people just for information, use the Add CC button to add their email addresses to the CC list.
If you want to add more documents, click Add Files and then browse and select the documents. (If you don't want to use the Advanced Options, skip the next optional step.)
(Optional) Click More Options, if you want to specify advanced options, such as signer authentication, reminders, and more.
By default, the Complete in Order setting is turned on. The numbers by the email addresses reflect the participation order. If you do not want to follow any particular order for signing, toggle the switch to Complete In Any Order. (Optional) Click Add Me, if you want to be included as a signer of the document.
Specify authentication type like Email, Password, Social Identity, Knowledge Based Authentication, or Phone.
Password Protect the PDF file.
Set a Completion Deadline.
Set Reminder for the recipients to take action.
Specify the Recipient's Language in the email sent.
Click Specify Where to Sign or Next.
The document is now ready for adding fields that you want the signers to fill in or sign.
Note: If you have added multiple documents, the documents are converted into PDFs and combined into a single file. The combined file is opened for you to add appropriate fields.
The Specify Where to Fill & Sign window is displayed showing options based on whether you have added one signer or multiple signers.
Simplified mode for single signer - If you've added one signer, you see the simplified option as shown below. To place a signature or another field, click at the desired location in the document and then set the field's properties from its context menu.
When you've placed all desired fields in the document, click Send. The document is sent for signature to the recipients and a confirmation notice is displayed.
A signer receives an email with a link to sign the agreement. Also, if the signer uses Acrobat DC or Acrobat Reader DC desktop application, the signer sees a notification that an agreement has been shared for signing. For more information, see Client Signing PDF Documents from Acrobat DC Pro.
Learn more about tracking your signatures: How to Track Your PDF Signatures in Acrobat DC Pro?