So long as the app in question is installed on your device and it supports PDF files, you will be able to export your report to it.
1) From the Projects screen, tap the Project you wish to share to go to its Summary screen.
2) Tap "Share Report" to generate and preview your report.
3) Tap the icon in the far top right of the screen to show the Export options available.
4) Tap "Open with..." to see all the available apps you can use.
If the app you wish to use isn't listed, tap on "More" at the end of the first row and enable it to appear in the list by tapping on the switch next to it. You can also change the order the apps are displayed on this screen. If you still can't find the app within this list, despite it being installed on your device, then it can't be used to share your report.